tying docs builds to 3.9 until mkdocs is upgraded

Author: chayim

.github/workflows/deploy-docs.yaml

@@ -1,6 +1,7 @@
 name: Deploy docs to website
 
 on:
+  workflow_dispatch:
   push:
     branches:
       - master
@@ -16,9 +17,9 @@ jobs:
     steps:
     - uses: actions/checkout@v2.1.1
     - name: Set up Python 3.x
-      uses: actions/setup-python@v1
+      uses: actions/setup-python@v2
       with:
-        python-version: '3.x'
+        python-version: '3.9'
     - name: Display Python version
       run: python -c "import sys; print(sys.version)"
     - name: Install docs dependencies