Remove unnecessary dep.

Author: dinowernli

src/main/java/me/dinowernli/grpc/prometheus/BUILD

@@ -4,7 +4,6 @@ java_library(
   name = "prometheus",
   srcs = glob(["*.java"]),
   deps = [
-    "//src/main/proto:hello_proto_grpc",
     "//third_party/grpc",
     "//third_party/prometheus",
   ],