Update Gradle and dependencies / Convert to Gradle Kotlin DSL / Introduce Spotless

[bwaldvogel]

No description provided.

[codecov]

Codecov Report

❌ Patch coverage is 97.22222% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 97.22%. Comparing base (b1f1b4d) to head (8733148).

Files with missing lines	Patch %	Lines
src/main/java/de/cronn/commons/lang/Action.java	81.81%	2 Missing ⚠️
...rc/main/java/de/cronn/commons/lang/StreamUtil.java	98.18%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main       #8      +/-   ##
============================================
+ Coverage     97.19%   97.22%   +0.02%     
  Complexity       57       57              
============================================
  Files             4        4              
  Lines           107      108       +1     
  Branches         11       11              
============================================
+ Hits            104      105       +1     
  Misses            3        3              

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