build: add protobuf-4.x-rc configuration to release please (googleapis#1848)

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

* chore: enable manifest option in release configuration

Author: diegomarquezp

.github/release-please.yml

@@ -42,3 +42,8 @@ branches:
     handleGHRelease: true
     releaseType: java-backport
     branch: 1.36.x
+  - bumpMinorPreMajor: true
+    handleGHRelease: true
+    releaseType: java-yoshi
+    branch: protobuf-4.x-rc
+    manifest: true