message: Bump tower-grpc to latest rev supporting tower-h2
  After this revision, the "tower-h2" feature no longer exists.
diff: @@ -26,9 +26,9 @@ tower-util = "0.1"
  [dependencies.tower-grpc]
  git = "https://github.com/tower-rs/tower-grpc"
  -rev = "0f15ae28f2a765e0cc38fe3d7e02a13aab7bdbd2"
  +rev = "137e970e4b563c4e06d41d31d04cabbfd1005f85"
  [build-dependencies.tower-grpc-build]
  git = "https://github.com/tower-rs/tower-grpc"
  -rev = "0f15ae28f2a765e0cc38fe3d7e02a13aab7bdbd2"
  +rev = "137e970e4b563c4e06d41d31d04cabbfd1005f85"
  features = ["tower-h2"]
  