Reflect Java 20 support in CLI help output

[3flex]

Java 20 targets were supported once #6258 was merged. This PR updates the CLI help output to match the supported target versions.

[detekt-ci]

	Warnings
⚠️	It looks like this PR contains functional changes without a corresponding test.
⚠️	This PR is approved with no milestone set. If merged, it won't appear in the detekt release notes.

Generated by 🚫 dangerJS against f1b45d9

[codecov]

Codecov Report

Merging #6277 (f1b45d9) into main (3bb6da4) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##               main    #6277   +/-   ##
=========================================
  Coverage     85.19%   85.19%           
  Complexity     4029     4029           
=========================================
  Files           568      568           
  Lines         13421    13421           
  Branches       2376     2376           
=========================================
  Hits          11434    11434           
  Misses          829      829           
  Partials       1158     1158           

Impacted Files	Coverage Δ
.../kotlin/io/gitlab/arturbosch/detekt/cli/CliArgs.kt	100.00% <ø> (ø)