ci: pin runner to node:22 and drop apt-get bootstrap

.forgejo/workflows/docs.yml

@@ -5,21 +5,18 @@ on:
       - main
 jobs:
   deploy:
-    runs-on: ubuntu-latest
+    runs-on: node:22
     steps:
       - uses: actions/checkout@v4
         with:
           fetch-depth: 0
 
-      - run: |
-          apt-get update && apt-get install -y python3 python3-pip python3-venv
-          python3 -m venv /tmp/venv
-          . /tmp/venv/bin/activate
-          python3 --version
-          pip3 install zensical
-          pip3 install -e .
+      - run: python3 --version
+      - run: pip3 install zensical
+      - run: pip3 install -e .
 
       - run: |
+          python3 -m venv /tmp/venv
           . /tmp/venv/bin/activate
           zensical build --clean