chore(deps): bump ash from 3.14.0 to 3.15.0 in the production-dependencies group - #125

Entity without __spark_metadata__ field is deprecated. Entity AshJsonApiWrapper.Endpoint does not define a `__spark_metadata__` field. This field is required to access source annotations. Add `__spark_metadata__: nil` to the defstruct for AshJsonApiWrapper.Endpoint.