Add test for HTTP default port 80 in https_check

[arpitjain099]

Follow-up to #267. @dav3r noted that #267 also added the http -> port 80 default but only the port 443 and explicit-port cases had tests, and it auto-merged before that could be addressed. This adds test_http_check_defaults_to_port_80 to cover the remaining branch.

It mirrors the existing test_https_check_defaults_to_port_443 test, just with an http endpoint and port 80.

Note: I couldn't run the suite locally (sslyze's nassl native lib won't load on my macOS), but I verified the logic directly: Endpoint("http", "root", "example.com").url is http://example.com, and the port parse in https_check returns 80 for an http URL with no explicit port. CI should exercise the full test on Linux like its siblings.

[jsf9k]

@arpitjain099 - Please let me know what you think of commits d659b65 and 01f6a13.

[dav3r]

LGTM, aside from the test name comment I mentioned. 👍

[arpitjain099]

Looks great @jsf9k - folding the two into a parametrized test_check_default_web_ports is cleaner than my separate test, and it picks up @dav3r's naming suggestion too. The unittest-parametrize approach and the mypy ignore for it both look good to me. Thanks for tightening it up.