fix: Kotlin Version Down To 2.2.21

[xeounxzxu]

Problem

Currently, CodeQL does not support Kotlin version 2.3.0.
(See login below.)

It also appears that the Kotlin version update was caused by a bot, not an intended Kotlin version update.

Error:  Failed to execute goal org.jetbrains.kotlin:kotlin-maven-plugin:2.3.0:compile (compile) on project querydsl-kotlin-codegen: Compilation failure -> [Help 1]
Error:  
Error:  To see the full stack trace of the errors, re-run Maven with the -e switch.
Error:  Re-run Maven using the -X switch to enable full debug logging.
Error:  
Error:  For more information about the errors and possible solutions, please read the following articles:
Error:  [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoFailureException
Error:  
Error:  After correcting the problems, you can resume the build with the command
Error:    mvn <args> -rf :querydsl-kotlin-codegen
Error: Process completed with exit code 1.

https://github.com/OpenFeign/querydsl/actions/runs/20293086393/job/58281207169

Solution

We recommend that you lower the version again and run the project as before.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 0.00%. Comparing base (34f66d2) to head (89f54b3).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@          Coverage Diff           @@
##           master   #1531   +/-   ##
======================================
  Coverage    0.00%   0.00%           
======================================
  Files         813     813           
  Lines       31466   31466           
  Branches     3614    3614           
======================================
  Misses      31466   31466           

Flag	Coverage Δ
db2	0.00% <ø> (?)
test	?

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[xeounxzxu]

@velo Can you check the PR?

[github-actions]

This pull request has been marked as stale due to inactivity.

[velo]

besides the codeQL, what is the reason for this?

[xeounxzxu]

@velo
I've submitted a PR solely to implement codeQL.
I'll close this PR and re-upload it after further review.