fix: configure dependabot to group react deps

[WilliamBergamin]

Summary

#1262 and #1261 are failing tests because dependabot is opening separate PRs for react and react-dom dependencies, I believe these dependencies must stay in sync in order for the tests to pass.

Once this PR is merged dependabot should open one single PR to replace #1262 and #1261

Testing

n/a

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.

[mwbrooks]

Thanks for putting this together!

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.96%. Comparing base (a1010fe) to head (832a953).
Report is 1 commits behind head on main.

Additional details and impacted files

@@ Coverage Diff @@## main #1263 +/- ##
=======================================
Coverage 90.96% 90.96% =======================================
Files 222 222 Lines 7501 7501 =======================================
Hits 6823 6823 Misses 678 678 

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