fix: now uses the right environment in github actions.

Author: jrfaller

.github/workflows/build-test-gumtree.yml

@@ -15,6 +15,7 @@ jobs:
   build-test-deploy:
     runs-on: ubuntu-latest
     container: gumtreediff/gumtree:latest
+    environment: MavenCentral
     if: ${{ github.event_name == 'pull_request' || !contains(github.event.head_commit.message, '[no ci]') || !startsWith(github.event.head_commit.message, 'doc') }}
     steps:
       - name: checkout gumtree