misc: add dummy GPG keys to JReleaser action

Author: 0marperez

.github/actions/jreleaser/action.yml

@@ -19,4 +19,8 @@ runs:
         export JRELEASER_MAVENCENTRAL_TOKEN="foo"
         export JRELEASER_GENERIC_TOKEN="foo"
         
+        export JRELEASER_GPG_PASSPHRASE="foo"
+        export JRELEASER_GPG_PUBLIC_KEY="${{ secrets.DUMMY_GPG_PUBLIC_KEY }}"
+        export JRELEASER_GPG_SECRET_KEY="${{ secrets.DUMMY_GPG_PRIVATE_KEY }}"
+        
         ./gradlew jreleaserFullRelease --dryrun --stacktrace