fix: broken python 3.10 unit test

[WilliamBergamin]

Summary

This PR aims to fix broken python 3.10 broken continuous integration pipeline that was relying on deprecated features of falcon

Testing

Continuous integration tests 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 91.30%. Comparing base (bddebca) to head (1121c97).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1509   +/-   ##
=======================================
  Coverage   91.30%   91.30%           
=======================================
  Files         228      228           
  Lines        7271     7271           
=======================================
  Hits         6639     6639           
  Misses        632      632           

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[vegeris]

Thanks for updating this!