Make repo fork-save

If this repo is forked, push to the forked repo, not to the original.
Also make sure the gitea link points back to this repo.

.gitea/workflows/deploy-pages.yml

@@ -16,7 +16,9 @@ jobs:
         uses: actions/checkout@v4
 
       - name: Build page
-        run: /opt/python-env/bin/zensical build
+        run: |
+            sed -i 's|repo_url[[:space:]]*=[[:space:]]*".*"|repo_url = "${{ github.server_url }}/${{ github.repository }}"|' zensical.toml
+            /opt/python-env/bin/zensical build
       
       - name: Configure Git
         run: |
@@ -30,5 +32,6 @@ jobs:
           mv site/* .
           git add .
           git commit -m "Update site - $(date)"
-          git push -f https://${{secrets.GITHUB_TOKEN}}@gitea.psi.ch/Controls/gitea-pages.git gitea-pages
+          REPO_URL=$(echo "${{ github.server_url }}/${{ github.repository }}.git" | sed 's|https://||')
+          git push -f https://${{ secrets.GITHUB_TOKEN }}@$REPO_URL gitea-pages