Update requirements.txt to use cisagov/trustymail

[Matthew-Grayson]

💡 Summary

requirements.txt points to a forked repo of trustymail (Matthew-Grayson/trustymail) due to an issue with the cisagov version downloading the public suffix list too often. The issue is fixed as of 12 September 2023.

Motivation and context

The cisagov repository is actively maintained unlike the fork, which I used as a stop gap.

[Matthew-Grayson]

There is an ongoing issue with cisagov/trustymail's psl-filename and psl-readonly arguments.