Add timezone property to timepicker block element

[seratch]

This pull request adds timezone property to timepicker block element. see also: slackapi/node-slack-sdk#1502

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

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

[codecov]

Codecov Report

Merging #1010 (635fcf4) into main (010182c) will decrease coverage by 0.08%.
The diff coverage is 0.00%.

@@             Coverage Diff              @@
##               main    #1010      +/-   ##
============================================
- Coverage     76.76%   76.67%   -0.09%     
+ Complexity     3688     3687       -1     
============================================
  Files           403      403              
  Lines         11120    11121       +1     
  Branches       1111     1111              
============================================
- Hits           8536     8527       -9     
- Misses         1909     1922      +13     
+ Partials        675      672       -3     

Impacted Files	Coverage Δ
...xtension/block/element/TimePickerElementBuilder.kt	87.50% <0.00%> (-5.84%)	⬇️
...va/com/slack/api/socket_mode/SocketModeClient.java	64.33% <0.00%> (-3.19%)	⬇️
...i/socket_mode/impl/SocketModeClientJavaWSImpl.java	63.81% <0.00%> (-2.64%)	⬇️

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[WilliamBergamin]

Looks good to me!

[seratch]

Thanks for the review!