added newline parameter to PatchSet::from_filename and test case with test diff file

[huichen-cs]

This is to add the newline parameter to PatchSet::from_filename.

This was originally submitted as pull request #83 that contains two changes

1. add the newline parameter and
2. add Github Actions configuration file.

This proposal only contains the changes for change 1 in the above. Change 2 will be submitted as a separate proposal following this one.

[matiasb]

Thanks! 👍