message: [libra-wallet] drop unused proto_conv dependency
  Closes:
  Approved by: mimoo
diff: @@ -28,9 +28,6 @@ package = "crypto"
  [dependencies.canonical_serialization]
  path = "../../common/canonical_serialization"
  -[dependencies.proto_conv]
  -path = "../../common/proto_conv"
  -
  [dependencies.failure]
  path = "../../common/failure_ext"
  package = "failure_ext"
  