error: spec path must end in `.spec.md`; use #[spec("file.spec.md")]
 --> tests/ui/fail_invalid_suffix.rs:3:1
  |
3 | #[spec("flight_core_contract.md")]
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |
  = note: this error originates in the attribute macro `spec` (in Nightly builds, run with -Z macro-backtrace for more info)