Simplify the action even more.

Author: arokem

.github/workflows/docbuild.yml

@@ -6,16 +6,12 @@ jobs:
   build:
 
     runs-on: ubuntu-latest
-    strategy:
-      matrix:
-        python-version: [3.9]
-
     steps:
     - uses: actions/checkout@v2
-    - name: Set up Python ${{ matrix.python-version }}
+    - name: Set up Python 3.9
       uses: actions/setup-python@v2
       with:
-        python-version: ${{ matrix.python-version }}
+        python-version: 3.9
     - name: Install
       run: |
         python -m pip install --upgrade pip