message: Add StarlarkRegex::TYPE
  Summary: Follow the recommended pattern.
diff: @@ -35,7 +35,7 @@ use crate::values::StarlarkValue;
  pub struct StarlarkRegex(pub Regex);
  impl StarlarkValue<'_> for StarlarkRegex {
  - starlark_type!("regex");
  + starlark_type!(StarlarkRegex::TYPE);
  fn get_methods() -> Option<&'static Methods> {
  static RES: MethodsStatic = MethodsStatic::new();
  @@ -43,6 +43,11 @@ impl StarlarkValue<'_> for StarlarkRegex {
  }
  }
  +impl StarlarkRegex {
  + /// The result of calling `type()` on regex.
  + pub const TYPE: &'static str = "regex";
  +}
  +
  impl Display for StarlarkRegex {
  fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  write!(f, "regex({:?})", &self.0.as_str())
  