cmd/protoc-gen-go-grpc: bump -version to 1.6.1 for release (#8879)

Addresses: #8870

protoc-gen-go-grpc v1.6.0 uses protobuf v1.36.10

https://github.com/grpc/grpc-go/blob/cmd/protoc-gen-go-grpc/v1.6.0/cmd/protoc-gen-go-grpc/go.mod

The following fix in protobuf v1.36.11 is required to address the linked
issue: https://go-review.googlesource.com/c/protobuf/+/713342

Release notes for protoc-gen-go-grpc:
* Upgrade protobuf dependency to `v1.36.11` to fix missing go_package
errors for Editions feature protos (e.g. cpp_features.proto).

RELEASE NOTES: N/A

Author: arjan-bal

balancer/grpclb/grpc_lb_v1/load_balancer_grpc.pb.go

@@ -42,7 +42,7 @@ import (
 	"google.golang.org/protobuf/types/pluginpb"
 )
 
-const version = "1.6.0"
+const version = "1.6.1"
 
 var requireUnimplemented *bool
 var useGenericStreams *bool