Update plugin dokka to v1.6.20

[renovate]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
org.jetbrains.dokka	1.6.10 -> 1.6.20

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Configuration

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[codecov]

Codecov Report

Merging #4717 (a91b64a) into main (471764c) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##               main    #4717   +/-   ##
=========================================
  Coverage     84.71%   84.71%           
  Complexity     3423     3423           
=========================================
  Files           490      490           
  Lines         11255    11255           
  Branches       2069     2069           
=========================================
  Hits           9535     9535           
  Misses          675      675           
  Partials       1045     1045           

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