build: add protobuf-4.x-rc configuration to release please (#2130)

* build: add protobuf-4.x-rc configuration to release please

* chore: set protobuf branch to manifest release

Author: diegomarquezp

.github/release-please.yml

@@ -34,3 +34,8 @@ branches:
     handleGHRelease: true
     releaseType: java-backport
     branch: 1.47.x
+  - bumpMinorPreMajor: true
+    handleGHRelease: true
+    releaseType: java-yoshi
+    branch: protobuf-4.x-rc
+    manifest: true