feat(platform): update PR target branch if baseBranch changed (#23010)

lib/modules/platform/azure/__snapshots__/index.spec.ts.snap

lib/modules/platform/azure/index.spec.ts

lib/modules/platform/azure/index.ts

lib/modules/platform/bitbucket-server/index.spec.ts

lib/modules/platform/bitbucket-server/index.ts

lib/modules/platform/bitbucket/index.spec.ts

lib/modules/platform/bitbucket/index.ts

lib/modules/platform/gitea/index.spec.ts

lib/modules/platform/gitea/index.ts

lib/modules/platform/gitea/types.ts

lib/modules/platform/gitlab/index.spec.ts

lib/modules/platform/gitlab/index.ts