ci: dry run java publish before release (#319)

The current Java publish `dry_run` only runs a plain `package`, so it
misses failures that are specific to the `deploy-to-ossrh` profile and
only show up during release publishing. This changes the dry run path to
execute `verify -P deploy-to-ossrh -Dgpg.skip=true`, which exercises
Javadoc generation and the publish profile without actually signing or
deploying artifacts.

I validated the new command locally on top of #318, and it successfully
builds the async and core-async modules through the same Javadoc path
that previously failed during release.

Author: Xuanwo

.github/workflows/java-publish.yml

@@ -70,7 +70,7 @@ jobs:
           github.event_name == 'pull_request' ||
           inputs.mode == 'dry_run'
         run: |
-          ./mvnw --batch-mode -DskipTests package
+          ./mvnw --batch-mode -DskipTests -Dgpg.skip=true verify -P deploy-to-ossrh
 
       - name: Java Publish
         if: |