Remove GPG_PASSPHRASE secret dependency since key has no passphrase

https://claude.ai/code/session_01ToqqHtNtg7kdm8TmAMZYe8

Author: claude

.github/workflows/release.yml

@@ -33,5 +33,5 @@ jobs:
         env:
           MAVEN_USERNAME: ${{ secrets.OSSRH_USERNAME }}
           MAVEN_PASSWORD: ${{ secrets.OSSRH_TOKEN }}
-          MAVEN_GPG_PASSPHRASE: ${{ secrets.GPG_PASSPHRASE }}
+          MAVEN_GPG_PASSPHRASE: ''
         run: mvn deploy -DskipTests=true