bump GitHub Actions to Node.js 24-compatible versions

checkout v4→v6, setup-python v5→v6, upload-pages-artifact v3→v4,
deploy-pages v4→v5.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: TrevorAustin

.github/workflows/build-and-deploy.yml

@@ -18,13 +18,13 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-python@v5
+      - uses: actions/checkout@v6
+      - uses: actions/setup-python@v6
         with:
           python-version: "3.12"
       - run: pip install -r requirements.txt
       - run: python build.py --base-url "/${{ github.event.repository.name }}"
-      - uses: actions/upload-pages-artifact@v3
+      - uses: actions/upload-pages-artifact@v4
         with:
           path: _site
 
@@ -36,4 +36,4 @@ jobs:
       url: ${{ steps.deployment.outputs.page_url }}
     steps:
       - id: deployment
-        uses: actions/deploy-pages@v4
+        uses: actions/deploy-pages@v5