ci: read the Central username from the secrets in the build phase

.github/workflows/build-and-deploy.yml

@@ -31,6 +31,7 @@ jobs:
                 || github.event.pull_request.head.repo.full_name == github.repository
               )
             }}
+          maven-central-username: ${{ secrets.MAVEN_CENTRAL_USERNAME }}
           maven-central-password: ${{ secrets.MAVEN_CENTRAL_PASSWORD }}
           signing-key: ${{ secrets.SIGNING_KEY }}
           signing-password: ${{ secrets.SIGNING_PASSWORD }}