Add Docker Hub login

Author: mrotteveel

.github/workflows/maven.yml

@@ -25,5 +25,12 @@ jobs:
         java-version: '17'
         distribution: 'temurin'
         cache: maven
+    - name: Login to Docker Hub
+      # PRs from forks don't have access to the secrets, skip Docker login and hope we don't hit the rate limit
+      if: ${{ !github.event.pull_request.head.repo.fork }}
+      uses: docker/login-action@v4
+      with:
+        username: ${{ secrets.DOCKERHUB_USERNAME }}
+        password: ${{ secrets.DOCKERHUB_TOKEN }}
     - name: Build with Maven
       run: mvn -B package --file pom.xml