Import GPG key in workflow

Already added the private key as a secret

Author: cgt

.github/workflows/maven.yml

@@ -13,6 +13,9 @@ jobs:
     steps:
     - uses: actions/checkout@v4
 
+    - name: Import GPG key
+      run: echo "${{ secrets.GPG_PRIVATE_KEY }}" | gpg --import --batch
+
     - name: Set up JDK 17
       uses: actions/setup-java@v4
       with: