Remove deprecated packages asynctest, codecov

[tomplus]

• replace asynctest with unittest (Python 3.8+) - it fixes Fix tests to work with Python 3.11 #234
• replace codecov with github actions codecov/codecov-actions to upload cov reports

[codecov]

Codecov Report

Patch coverage: 85.45% and project coverage change: -2.36 ⚠️

Comparison is base (5bfb913) 26.99% compared to head (7ba0874) 24.63%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #251      +/-   ##
==========================================
- Coverage   26.99%   24.63%   -2.36%     
==========================================
  Files         728      728              
  Lines       97991    97979      -12     
==========================================
- Hits        26451    24142    -2309     
- Misses      71540    73837    +2297     

Impacted Files	Coverage Δ
kubernetes_asyncio/e2e_test/base.py	0.00% <0.00%> (ø)
kubernetes_asyncio/e2e_test/test_api.py	0.00% <0.00%> (ø)
kubernetes_asyncio/e2e_test/test_batch.py	0.00% <0.00%> (ø)
kubernetes_asyncio/e2e_test/test_client.py	0.00% <0.00%> (ø)
kubernetes_asyncio/config/exec_provider_test.py	100.00% <100.00%> (ø)
kubernetes_asyncio/config/google_auth_test.py	100.00% <100.00%> (+7.69%)	⬆️
kubernetes_asyncio/config/kube_config_test.py	94.76% <100.00%> (+0.22%)	⬆️
kubernetes_asyncio/config/openid_test.py	100.00% <100.00%> (ø)
kubernetes_asyncio/stream/ws_client_test.py	100.00% <100.00%> (+4.08%)	⬆️
kubernetes_asyncio/utils/create_from_yaml_test.py	100.00% <100.00%> (+10.00%)	⬆️
... and 1 more

... and 116 files with indirect coverage changes

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