health: publish test results to code cov

[WilliamBergamin]

Summary

This PR is inspired by slackapi/node-slack-sdk#2178

It updates the CI pipeline to publish the test results to codcov and provide some neat reporting details

Testing

Category

• slack_sdk.web.WebClient (sync/async) (Web API client)
• slack_sdk.webhook.WebhookClient (sync/async) (Incoming Webhook, response_url sender)
• slack_sdk.socket_mode (Socket Mode client)
• slack_sdk.signature (Request Signature Verifier)
• slack_sdk.oauth (OAuth Flow Utilities)
• slack_sdk.models (UI component builders)
• slack_sdk.scim (SCIM API client)
• slack_sdk.audit_logs (Audit Logs API client)
• slack_sdk.rtm_v2 (RTM client)
• /docs (Documents)
• /tutorial (PythOnBoardingBot tutorial)
• tests/integration_tests (Automated tests for this library)

Requirements

• I've read and understood the Contributing Guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.
• I've run python3 -m venv .venv && source .venv/bin/activate && ./scripts/run_validation.sh after making the changes.

[mwbrooks]

❤️ Love it!

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 85.36%. Comparing base (4d15fde) to head (c4bf7a3).
Report is 1 commits behind head on main.

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@ Coverage Diff @@## main #1677 +/- ##
==========================================
+ Coverage 85.32% 85.36% +0.04% 
==========================================
Files 113 113 Lines 12808 12808 ==========================================
+ Hits 10928 10934 +6 + Misses 1880 1874 -6 

☔ View full report in Codecov by Sentry.
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[zimeg]

LGTM! And these results are so far more interesting to me than those before. Perhaps a bias of what's recent:

https://app.codecov.io/gh/slackapi/python-slack-sdk/tests/code-cov-test-reporting

[zimeg]

🤖 ✨

It's so great that pytest has built in junit support!