text: Title: Pipeline can't be run with env file having .yml suffix
  Body: ### Description
  Pipeline can't be run with `env.yml` file. It seems it won't get read at all since variables stated in the `env.yml` are unknown to the pipeline run. Renaming file to `env.yaml` solved the issue for me. 
  
  ### Replication
  Files for replication of minimal example are attached [here](https://github.com/ploomber/projects/files/8303640/test.zip).
  
  ### Task
  It would be nice to not be dependent on the suffix. Adjust the code, so it treats `.yaml` and `.yml` suffixes of `env` file equally.