Merge pull request #1026 from cderici/resolve-build-problems-3.3.1.0

#1026

#### Description

This solves 2 problems with the latest release (also described in [this comment](#1025 (comment))):

1. We depend on the `packaging` module, but didn't include it in the `setup.py` (because our testing and dev environments have tox installed and tox satisfies that requirement for itself, so we didn't notice).
2. We [accidentally depend](https://github.com/juju/python-libjuju/blob/905de781cb92041dcae158412861464d87a8bb77/juju/version.py#L18) on the static [VERSION ](https://github.com/juju/python-libjuju/blob/master/VERSION) file where we keep track of the version of pylibjuju.

This change fixes #1025, solving these issues by:

1. Adding the `packaging` to the required modules.
2. Removing the file `VERSION`, and moving the static version information into the `version.py` module (just like in Juju) and use that information from there. The places that dynamically use that information (outside of the juju modules) are i) `setup.py` to get the version info into the build, ii) `Makefile` to use it in the release target iii) `docs/config.py` for building the docs. All of these spots are updated to use the info within the `version.py`.

#### QA Steps

We'll use the steps described in #1025. After pulling the branch in this PR;

- Create a new virtual env:

```
python -m venv venv
```

- Activate it:

```
source venv/bin/activate
```

- Build pylibjuju at this spot:

```
python setup.py sdist
```

- The sdist build will create a `dist/juju-3.3.1.0.tar.gz`, so install that:

```
pip install dist/juju-3.3.1.0.tar.gz
```

- Now try to import a `Controller`.

```
python3 -c "from juju.controller import Controller"
```

Without the (1)st change in this PR, this command would result in:

```
ModuleNotFoundError: No module named 'packaging'
```

And without the (2)nd change, this command would error with 

```
FileNotFoundError: [Errno 2] No such file or directory: '......./venv/lib/python3.10/site-packages/VERSION'
```

But with this change, we shouldn't see either (or any other) error. I.e., the command should succeed with no problems.

#### Notes & Discussion

Note that this changes the release process. In particular where we need to manually change the version information is moved into the `version.py` module (the release process document will be updated right before this PR is merged).

Moreover, we need to make a patch release (`3.3.1.1`) after this for these changes to take effect (i.e. for pylibjuju to be usable in the environments where it's installed as a dependency).

JUJU-5484

Author: jujubot

MANIFEST.in

@@ -1,4 +1,4 @@
-include *.py CONTRIBUTORS LICENSE README.rst VERSION
+include *.py CONTRIBUTORS LICENSE README.rst
 recursive-include juju *.py
 recursive-include examples *.py
 recursive-include docs *.rst

Makefile

@@ -1,7 +1,7 @@
 BIN := .tox/py3/bin
 PY := $(BIN)/python3
 PIP := $(BIN)/pip3
-VERSION=$(shell cat VERSION)
+VERSION := $(shell $(PY) -c "from juju.version import CLIENT_VERSION; print(CLIENT_VERSION)")
 
 .PHONY: clean
 clean:

VERSION

@@ -21,13 +21,16 @@
 from pathlib import Path
 
 here = Path(__file__).absolute().parent
-version = (here.parent / 'VERSION').read_text().strip()
+
 
 # If extensions (or modules to document with autodoc) are in another directory,
 # add these directories to sys.path here. If the directory is relative to the
 # documentation root, use os.path.abspath to make it absolute, like shown here.
 sys.path.insert(0, os.path.abspath('..'))
 
+from juju.version import CLIENT_VERSION
+version = CLIENT_VERSION
+
 # -- General configuration ------------------------------------------------
 
 # If your documentation needs a minimal Sphinx version, state it here.

docs/conf.py

@@ -12,4 +12,5 @@ paramiko
 macaroonbakery
 toposort
 python-dateutil
-kubernetes
+kubernetes
+packaging

docs/requirements.txt

@@ -1,19 +1,8 @@
 # Copyright 2023 Canonical Ltd.
 # Licensed under the Apache V2, see LICENCE file for details.
 
-import pathlib
-import re
-
 LTS_RELEASES = ["jammy", "focal", "bionic", "xenial", "trusty", "precise"]
 
 DEFAULT_ARCHITECTURE = 'amd64'
 
-# CLIENT_VERSION (that's read from the VERSION file) is the highest Juju server
-# version that this client supports.
-# Note that this is a ceiling. CLIENT_VERSION <= juju-controller-version works.
-# For CLIENT_VERSION < juju-controller-version (strictly smaller), we emit a warning
-# to update the client to the latest.
-# However, for any CLIENT_VERSION > juju-controller-version, a "client incompatible
-# with server" will be returned by the juju controller.
-VERSION_FILE_PATH = pathlib.Path(__file__).parent.parent / 'VERSION'
-CLIENT_VERSION = re.search(r'\d+\.\d+\.\d+', open(VERSION_FILE_PATH).read().strip()).group()
+CLIENT_VERSION = "3.3.1.0"

juju/version.py

@@ -5,6 +5,8 @@
 
 from setuptools import find_packages, setup
 
+from juju.version import CLIENT_VERSION
+
 here = Path(__file__).absolute().parent
 readme = here / 'docs' / 'readme.rst'
 changelog = here / 'docs' / 'changelog.rst'
@@ -13,11 +15,10 @@
     changelog.read_text()
 )
 long_description_content_type = 'text/x-rst'
-version = here / 'VERSION'
 
 setup(
     name='juju',
-    version=version.read_text().strip(),
+    version=CLIENT_VERSION.strip(),
     packages=find_packages(
         exclude=["*.tests", "*.tests.*", "tests.*", "tests"]),
     package_data={'juju': ['py.typed']},
@@ -32,6 +33,7 @@
         'typing_inspect>=0.6.0',
         'kubernetes>=12.0.1',
         'hvac',
+        'packaging',
     ],
     include_package_data=True,
     maintainer='Juju Ecosystem Engineering',

setup.py

@@ -40,6 +40,7 @@ deps =
     websockets
     kubernetes
     hvac
+    packaging
 
 [testenv:docs]
 deps =