Replace mypy link with one that supports HTTPS
Replace mypy link with one that supports HTTPS

It seems like pointing to PyPI.org is reasonable?

Co-Authored-By: Keegan Helmbrecht <caa5d918428bea6fc9e58ff827b016762bf5619d@gmail.com>

conorsch/securedrop,conorsch/securedrop,conorsch/securedrop,conorsch/securedrop,conorsch/securedrop