fix: Update repository URL in all workflow files

- Fix checkout URLs in update-production-secrets.yml
- Fix checkout URLs in security-scan.yml
- Fix checkout URLs in test-registry.yml
- Change from repository.michaelschiemer.de:5000 to git.michaelschiemer.de

.gitea/workflows/security-scan.yml

@@ -27,7 +27,7 @@ jobs:
           # Use CI token if available, otherwise try public access
           if [ -n "${{ secrets.CI_TOKEN }}" ]; then
             git clone --depth 1 --branch "$REF_NAME" \
-              "https://${{ secrets.CI_TOKEN }}@repository.michaelschiemer.de:5000/${REPO}.git" \
+              "https://${{ secrets.CI_TOKEN }}@git.michaelschiemer.de/${REPO}.git" \
               /workspace/repo
           else
             # Try public HTTPS (works if repository is public)