Fix trybuilds (#179)

Author: illicitonion

num_enum/tests/try_build/compile_fail/conflicting_derive.stderr_nightly

@@ -0,0 +1,20 @@
+error[E0119]: conflicting implementations of trait `num_enum::CannotDeriveBothFromPrimitiveAndTryFromPrimitive` for type `Numbers`
+ --> tests/try_build/compile_fail/conflicting_derive.rs:1:35
+  |
+1 | #[derive(num_enum::FromPrimitive, num_enum::TryFromPrimitive)]
+  |          -----------------------  ^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation for `Numbers`
+  |          |
+  |          first implementation here
+  |
+  = note: this error originates in the derive macro `num_enum::TryFromPrimitive` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0119]: conflicting implementations of trait `TryFrom<u8>` for type `Numbers`
+ --> tests/try_build/compile_fail/conflicting_derive.rs:1:35
+  |
+1 | #[derive(num_enum::FromPrimitive, num_enum::TryFromPrimitive)]
+  |                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^
+  |
+  = note: conflicting implementation in crate `core`:
+          - impl<T, U> TryFrom<U> for T
+            where U: Into<T>;
+  = note: this error originates in the derive macro `num_enum::TryFromPrimitive` (in Nightly builds, run with -Z macro-backtrace for more info)

num_enum/tests/try_build/compile_fail/custom_error_type_parsing.stderr

@@ -19,7 +19,7 @@ error: expected `name` or `constructor`
 error: num_enum attribute must have at most one error_type
   --> tests/try_build/compile_fail/custom_error_type_parsing.rs:29:76
    |
-29 | #[num_enum(error_type(name = CustomError, constructor = CustomError::new), error_type(name = CustomError, constructor = CustomError::new))]
+29 | #[num_enum(error_type(name = CustomError, constructor = CustomError::new), error_type(name = CustomError, constructor = CustomError:...
    |                                                                            ^^^^^^^^^^
 
 error: num_enum attribute must have at most one error_type