Coercion issue for signals

[acumartini]

Ran into a coercion error when using the new signals patterns.

SQLMesh version: 0.158.1

Example signal def with fields related to the errors I am seeing:

@signal()
def airflow_task(
    environment: str,
) -> DatetimeRanges:

Example usage:

signals [
    airflow_task(
      environment := @gateway,    )
  ]

Example coercion error:

[ERROR] Coercion of expression '@gateway' to type '<class 'str'>' failed. Using non coerced expression at '...sql'