Fix GitHub Actions-based snapshot deployment

Fixes https://github.com/google/google-java-format/issues/547

PiperOrigin-RevId: 344903246
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 468d9e9..a14629f 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -80,4 +80,7 @@
           server-username: CI_DEPLOY_USERNAME
           server-password: CI_DEPLOY_PASSWORD
       - name: 'Publish'
+        env:
+          CI_DEPLOY_USERNAME: ${{ secrets.CI_DEPLOY_USERNAME }}
+          CI_DEPLOY_PASSWORD: ${{ secrets.CI_DEPLOY_PASSWORD }}
         run: mvn source:jar deploy -B -DskipTests=true -Dinvoker.skip=true -Dmaven.javadoc.skip=true