[deps] Remove coveralls in favor of coverage

The `coveralls` Python package is no longer actively maintained and is
not needed locally.

Coverage reports are not uploaded to Coveralls from local builds.
On CI, the `coverallsapp/github-action@v2` GitHub Action handles
uploading coverage reports to coveralls.io in CI.

Author: pandafy

setup.py

@@ -37,7 +37,7 @@
             'black~=23.12.1',
             'flake8~=7.1.0',
             'isort~=5.13.2',
-            'coverage~=7.7.1',
+            'coverage~=7.6.1',
             'tblib~=3.0.0',
             'docstrfmt~=1.8.0',
         ],