Update Milestone URL to Point to Central

Author: jzheaux

.github/workflows/continuous-integration-workflow.yml

@@ -61,7 +61,7 @@ jobs:
     with:
       should-perform-release: ${{ needs.deploy-artifacts.outputs.artifacts-deployed }}
       project-version: ${{ needs.deploy-artifacts.outputs.project-version }}
-      milestone-repo-url: https://repo.spring.io/artifactory/milestone
+      milestone-repo-url: https://repo1.maven.org/maven2
       release-repo-url: https://repo1.maven.org/maven2
       artifact-path: org/springframework/ldap/spring-ldap-core
       slack-announcing-id: spring-ldap-announcing