third-party/rust: Disable default features in num_enum crate

Summary: The default platform adds "std" back in, but this allows the no_std universe to build with no std..

Reviewed By: jsgf

Differential Revision: D54934898

fbshipit-source-id: b64c170aee976eda1cffde1ff18bccc24c6c1267

Cargo.toml

@@ -25,7 +25,7 @@ path = "print_cst.rs"
 bstr = { version = "1.4.0", features = ["serde", "std", "unicode"] }
 clap = { version = "3.2.25", features = ["derive", "env", "regex", "unicode", "wrap_help"] }
 itertools = "0.11.0"
-num_enum = "0.5"
+num_enum = { version = "0.5", default-features = false }
 ocamlrep = { path = "vendor/ocaml/interop/ocamlrep" }
 ocamlrep_ocamlpool = { path = "vendor/ocaml/interop/ocamlrep_ocamlpool" }
 phf = { version = "0.11", features = ["macros"] }