chore: fix test warnings across test suite

[WilliamBergamin]

Summary

This PR aims to fix some warnings that were showing up in our unit tests 🙏

Testing

CI should be sufficient

Category

• slack_bolt.App and/or its core components
• slack_bolt.async_app.AsyncApp and/or its core components
• Adapters in slack_bolt.adapter
• Document pages under /docs
• Others

Requirements

Please read the Contributing guidelines and Code of Conduct before creating this issue or pull request. By submitting, you are agreeing to those rules.

• 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 ./scripts/install_all_and_run_tests.sh after making the changes.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.31%. Comparing base (6e57716) to head (edd539f).
⚠️ Report is 1 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1468   +/-   ##
=======================================
  Coverage   91.31%   91.31%           
=======================================
  Files         229      229           
  Lines        7266     7266           
=======================================
  Hits         6635     6635           
  Misses        631      631           

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[zimeg]

@WilliamBergamin Another amazing change in care for this project 🧪 ✨

Please merge when's right but I left a curious question if the answer is quick-

[zimeg]

👁️‍🗨️ question: Does this sqlite implementation not use the file system? I haven't explored these tests much but found this surprising at glance!

[WilliamBergamin]

Good point I found another way to silence the django warning 🙏