fix(ci): replace docker-based version extraction with grep

The Docker-in-Docker volume mount fails in host execution mode
because $PWD resolves to the runner container path, not the host
path. Use grep to extract the version directly from constants.php.

.forgejo/workflows/build.yml

@@ -20,7 +20,7 @@ jobs:
       - name: Get version
         id: version
         run: |
-          VERSION=$(docker run --rm -v "$PWD:/app" -w /app php:8.2-alpine3.16 php bootstrap/getVersion.php)
+          VERSION=$(grep -oP "'version' => '\K[^']+" config/constants.php)
           echo "VERSION=${VERSION}" >> "$GITHUB_OUTPUT"
           echo "Building version: ${VERSION}"