fix: bump jetty version

[WilliamBergamin]

vulnerability in jetty 9.4.56 bumping to 9.4.57 should fix the issue

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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[mwbrooks]

✅ 🔒 🚀

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 73.02%. Comparing base (cbefe51) to head (03954e7).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #1494      +/-   ##
============================================
+ Coverage     72.87%   73.02%   +0.14%     
- Complexity     4373     4381       +8     
============================================
  Files           475      475              
  Lines         14244    14244              
  Branches       1447     1447              
============================================
+ Hits          10381    10402      +21     
+ Misses         3007     2988      -19     
+ Partials        856      854       -2     

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