chore: fix aioresponses support and update codecoverage gpg

[karel-rehor]

Proposed Changes

Note that this client library is currently in maintenance mode only, so maintenance time is a factor in implementing these changes. There are no plans to remove support for older python versions, nor to make newer python versions a standard reference point.

aioresponses

The most recent release of the aioresponses library presents a couple of problems.

1. It no longer supports Python versions older than 3.10
2. It requires support of a newer version of aiohttp, the absence of which leads to compilation problems, such as mismatched constructor signatures for ClientResponse. (aiohttp also dropped support for python 3.7 and older a few years ago).

solution:

1. fix aioresponses to the legacy 0.7.3 release
2. conditionally include aioresponses and tests leveraging this library in async tests.
   1. this should fix nightly builds
   2. the marked async tests should still be run at least in earlier python versions.
   3. it allows test suites for newer python versions to complete, albeit without the three tests in question.

codecoverage

Endpoints for gpg data have changed. These have been updated.

Checklist

• CHANGELOG.md updated. N.A.
• Rebased/mergeable
• A test has been added if appropriate N.A.
• pytest tests completes successfully
• Commit messages are conventional
• Sign CLA (if not already signed)