fix: resolve duplicate GitHub Pages artifacts in docs deployment

Downgraded GitHub Actions in .github/workflows/docs.yml to stable versions
to resolve a conflict where multiple artifacts named 'github-pages' were
found, causing deployment failures.

Changes:
- actions/configure-pages@v6 -> v5
- actions/checkout@v6 -> v4
- actions/setup-python@v6 -> v5
- actions/upload-pages-artifact@v5 -> v3
- actions/deploy-pages@v5 -> v4

Co-authored-by: MessiasLima <10220064+MessiasLima@users.noreply.github.com>

Author: google-labs-jules[bot]

.github/workflows/docs.yml

@@ -20,13 +20,13 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Configure GitHub pages
-        uses: actions/configure-pages@v6
+        uses: actions/configure-pages@v5
 
       - name: Checkount main branch
-        uses: actions/checkout@v6
+        uses: actions/checkout@v4
 
       - name: Setup Python 3.x
-        uses: actions/setup-python@v6
+        uses: actions/setup-python@v5
         with:
           python-version: 3.x
 
@@ -37,10 +37,10 @@ jobs:
         run: zensical build --clean
 
       - name: Upload website artifacts
-        uses: actions/upload-pages-artifact@v5
+        uses: actions/upload-pages-artifact@v3
         with:
           path: site
 
       - name: Deploy website
-        uses: actions/deploy-pages@v5
+        uses: actions/deploy-pages@v4
         id: deployment