Repoint kattu ref to gpgupdate-masterj21 for GPG_PRIVATE_KEY support

The master-java21 branch of mosip/kattu does not declare
GPG_PRIVATE_KEY as an accepted secret on maven-build.yml/
maven-publish-to-nexus.yml yet; that support currently only exists
on the gpgupdate-masterj21 branch. Repoint the affected job refs so
the newly-added secret is actually valid, per CodeRabbit review on
mosip/commons#1845.

Signed-off-by: Chetan Kumar Hirematha <chetankumar.h.239@gmail.com>

Author: chetankh239

.github/workflows/push-trigger.yml

@@ -24,7 +24,7 @@ on:
 
 jobs:
   build-maven-audit-manager:
-    uses: mosip/kattu/.github/workflows/maven-build.yml@master-java21
+    uses: mosip/kattu/.github/workflows/maven-build.yml@gpgupdate-masterj21
     with:
       SERVICE_LOCATION: ./kernel/
       BUILD_ARTIFACT: kernel-auditmanager-service
@@ -39,7 +39,7 @@ jobs:
   publish_to_nexus:
     if: "${{ !contains(github.ref, 'master') && github.event_name != 'pull_request' && github.event_name != 'release' && github.event_name != 'prerelease' && github.event_name != 'publish' }}"
     needs: build-maven-audit-manager
-    uses: mosip/kattu/.github/workflows/maven-publish-to-nexus.yml@master-java21
+    uses: mosip/kattu/.github/workflows/maven-publish-to-nexus.yml@gpgupdate-masterj21
     with:
       SERVICE_LOCATION: ./kernel/
     secrets: