Bump com.google.protobuf:protoc from 3.21.12 to 4.28.1

Bumps [com.google.protobuf:protoc](https://github.com/protocolbuffers/protobuf) from 3.21.12 to 4.28.1.
- [Release notes](https://github.com/protocolbuffers/protobuf/releases)
- [Changelog](https://github.com/protocolbuffers/protobuf/blob/main/protobuf_release.bzl)
- [Commits](https://github.com/protocolbuffers/protobuf/commits)

---
updated-dependencies:
- dependency-name: com.google.protobuf:protoc
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

grpc/build.gradle

@@ -39,13 +39,13 @@ dependencies {
 def artifactName = 'com.google.protobuf:protoc:3.14.0:osx-x86_64'
 switch (org.gradle.internal.os.OperatingSystem.current()) {
     case org.gradle.internal.os.OperatingSystem.LINUX:
-        artifactName = "com.google.protobuf:protoc:3.21.12"
+        artifactName = "com.google.protobuf:protoc:4.28.1"
         break;
     case org.gradle.internal.os.OperatingSystem.MAC_OS:
         artifactName = "com.google.protobuf:protoc:3.14.0:osx-x86_64"
         break;
     case org.gradle.internal.os.OperatingSystem.WINDOWS:
-        artifactName = "com.google.protobuf:protoc:3.21.12"
+        artifactName = "com.google.protobuf:protoc:4.28.1"
         break;
 }