Add keycloak-testing branch to workflow triggers

This update modifies the GitHub Actions workflow for building the
Keycloak chart. In addition to the existing trigger for the
main branch, a new trigger has been added for the
keycloak-testing branch. This change allows for more flexible
testing and deployment scenarios by enabling the workflow to
run on changes pushed to the keycloak-testing branch.

No breaking changes are introduced with this update, and the
workflow paths remain unchanged, still focusing on the
"charts/keycloak/Chart.yaml" file.

.gitea/workflows/build-chart-keycloak.yml

@@ -3,6 +3,7 @@ on:
   push:
     branches:
       - main
+      - keycloak-testing
     paths:
       - "charts/keycloak/Chart.yaml"