Upgrade okhttp to 4.12.0 for security fixes

[seratch]

Upgrading okhttp to the latest version is required for publishing a new version.

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

• [ ] bolt (Bolt for Java)
• [ ] bolt-{sub modules} (Bolt for Java - optional modules)
• [x] 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

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

[codecov[bot]]

Codecov Report

Merging #1226 (4810c3f) into main (33900b0) will increase coverage by 0.09%. The diff coverage is n/a.

@@             Coverage Diff              @@
##               main    #1226      +/-   ##
============================================
+ Coverage     74.72%   74.81%   +0.09%     
- Complexity     4071     4075       +4     
============================================
  Files           437      437              
  Lines         12855    12855              
  Branches       1298     1298              
============================================
+ Hits           9606     9618      +12     
+ Misses         2491     2477      -14     
- Partials        758      760       +2     

see 3 files with indirect coverage changes

:mega: We’re building smart automated test selection to slash your CI/CD build times. Learn more