ci: push to ghcr.io (again)

[mccutchen]

The change in #200 to push images to ghcr.io in addition to docker hub failed with an authentication error:

ERROR: failed to solve: failed to push ghcr.io/***/go-httpbin:v2.17.0: unexpected status from POST request to https://ghcr.io/v2/***/go-httpbin/blobs/uploads/: 403 Forbidden

Here's one attempt to fix it, while also updating various deps and improving other metadata.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.50%. Comparing base (05a9dfd) to head (1f2bb7a).
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #201   +/-   ##
=======================================
  Coverage   94.50%   94.50%           
=======================================
  Files          10       10           
  Lines        2185     2185           
=======================================
  Hits         2065     2065           
  Misses         84       84           
  Partials       36       36           

🚀 New features to boost your workflow:

• ❄ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.