fix: configure dependabot to group react deps

[WilliamBergamin]

#1446 and #1445 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 #1446 and #1445

Category (place an x in each of the [ ])

• bolt (Bolt for Java)
• bolt-{sub modules} (Bolt for Java - optional modules)
• slack-api-client (Slack API Clients)
• slack-api-model (Slack API Data Models)
• slack-api-*-kotlin-extension (Kotlin Extensions for Slack API Clients)
• slack-app-backend (The primitive layer of Bolt for Java)

Requirements

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 73.05%. Comparing base (a2120d2) to head (9a131ac).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##               main    #1447   +/-   ##
=========================================
  Coverage     73.05%   73.05%           
  Complexity     4378     4378           
=========================================
  Files           475      475           
  Lines         14243    14243           
  Branches       1447     1447           
=========================================
  Hits          10405    10405           
  Misses         2984     2984           
  Partials        854      854           

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[mwbrooks]

👌🏻