Bump io.grpc:grpc-bom

Bumps the maven group with 1 update in the /protobuf-maven-plugin/src/it/setup directory: [io.grpc:grpc-bom](https://github.com/grpc/grpc-java).


Updates `io.grpc:grpc-bom` from 1.80.0 to 1.81.0
- [Release notes](https://github.com/grpc/grpc-java/releases)
- [Commits](grpc/grpc-java@v1.80.0...v1.81.0)

---
updated-dependencies:
- dependency-name: io.grpc:grpc-bom
  dependency-version: 1.81.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: maven
...

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

Author: dependabot[bot]

protobuf-maven-plugin/src/it/setup/pom.xml

@@ -33,7 +33,7 @@
   <packaging>pom</packaging>
 
   <properties>
-    <grpc.version>1.80.0</grpc.version>
+    <grpc.version>1.81.0</grpc.version>
     <kotlin.version>2.3.21</kotlin.version>
     <proto-google-common-protos.version>2.70.0</proto-google-common-protos.version>
     <scala.version>3.8.3</scala.version>