message: Allow syn-1.0.33
  Summary: I tested this version of syn by pinning it with =1.0.33. Anything lower clashed with serde_derive v1.0.118, so couldn't be tested, and would be unlikely to form a valid build plan anyway.
diff: @@ -13,7 +13,7 @@ proc-macro = true
  [dependencies]
  proc-macro2 = "1.0"
  -syn = {version = "1.0.57", features = ["full"]}
  +syn = {version = "1.0.33", features = ["full"]}
  # @oss-disable: gazebo = { path = "../../gazebo/gazebo", features = ["str_pattern_extensions"] }
  gazebo = { git = "https://github.com/facebookincubator/gazebo", features = ["str_pattern_extensions"] } # @oss-enable
  quote = "1.0.3"
  