GitHub Actions: Pin ubuntu version and fix package versions (#2915)

.github/workflows/docs.yml

@@ -17,7 +17,7 @@ on:
 jobs:
   spelling:
     name: Spellcheck
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04
     steps:
       - uses: actions/checkout@v2
       - name: Set up Python 3.8
@@ -31,7 +31,7 @@ jobs:
           restore-keys: |
             ${{ runner.os }}-pip-
       - name: Install system packages
-        run: sudo apt update && sudo apt install enchant hunspell aspell-en
+        run: sudo apt update && sudo apt install enchant-2 hunspell aspell-en
       - name: Install Dependencies
         run: pip3 install -Ur requirements.txt
         working-directory: ./doc