fix(protobuf-deps): use latest grpc and protobuf

v3/go.mod

@@ -1,13 +1,14 @@
 module github.com/newrelic/go-agent/v3
 
-go 1.20
+go 1.21
 
 require (
-	google.golang.org/protobuf v1.5.3
-	google.golang.org/grpc v1.56.3
+	google.golang.org/grpc v1.65.0
+	google.golang.org/protobuf v1.34.2
 )
 
-
 retract v3.22.0 // release process error corrected in v3.22.1
 
 retract v3.25.0 // release process error corrected in v3.25.1
+
+retract v3.34.0 // this release erronously referred to and invalid protobuf dependency

v3/internal/com_newrelic_trace_v1/README.md

@@ -4,14 +4,17 @@ To generate the `v1.pb.go` code, run the following from the top level
 `github.com/newrelic/go-agent` package:
 
 ```
-protoc --go_out=paths=source_relative,plugins=grpc:. v3/internal/com_newrelic_trace_v1/v1.proto
+protoc --go_out=. --go_opt=paths=source_relative \
+    --go-grpc_out=. --go-grpc_opt=paths=source_relative \
+    v3/internal/com_newrelic_trace_v1/v1.proto
 ```
 
-Be mindful which version of `protoc-gen-go` you are using. Upgrade
-`protoc-gen-go` to the latest with:
+Be mindful which version of `protoc-gen-go` and `protoc-gen-go-grpc` you are using.
+Upgrade both of these tools to the latest with:
 
 ```
-go get -u github.com/golang/protobuf/protoc-gen-go
+go install google.golang.org/protobuf/cmd/protoc-gen-go@latest
+go install google.golang.org/grpc/cmd/protoc-gen-go-grpc@latest
 ```
 
 ## When you regenerate the file