Use Poetry to install and run linters (#7)

This ensures that developers and the CI are using the same versions of our linting tools. As a bonus, Poetry is now installed using the install script, ensuring that its dependencies don't conflict with ours.

Author: velovix

.circleci/config.yml

@@ -22,9 +22,11 @@ jobs:
       - image: circleci/python:3.6
     steps:
       - checkout
-      - run: pip3 install --upgrade mypy black
-      - run: black --check .
-      - run: mypy -p "brainframe.cli"
+      - run: "curl -sSL https://raw.githubusercontent.com/python-poetry/poetry/master/get-poetry.py
+          | python3 - --version 1.1.0"
+      - run: poetry install --no-root
+      - run: poetry run black --check .
+      - run: poetry run mypy -p "brainframe.cli"
   upload_to_pypi:
     docker:
       - image: circleci/python:3.6
@@ -33,6 +35,7 @@ jobs:
 
     steps:
       - checkout
-      - run: pip3 install --upgrade poetry
+      - run: "curl -sSL https://raw.githubusercontent.com/python-poetry/poetry/master/get-poetry.py
+          | python3 - --version 1.1.0"
       - run: poetry build
       - run: POETRY_HTTP_BASIC_PYPI_PASSWORD=${PYPI_PASSWORD} poetry publish