Update pandoc/core Docker tag to v3

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
pandoc/core	docker	major	2.19 -> 3.1

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[codecov-commenter]

Codecov Report

Merging #359 (94e4c35) into main (b7ed32c) will increase coverage by 0.63%.
The diff coverage is n/a.

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@@             Coverage Diff              @@
##               main     #359      +/-   ##
============================================
+ Coverage     77.42%   78.06%   +0.63%     
- Complexity      454      457       +3     
============================================
  Files            86       86              
  Lines          1094     1094              
  Branches         72       72              
============================================
+ Hits            847      854       +7     
+ Misses          208      204       -4     
+ Partials         39       36       -3     

see 1 file with indirect coverage changes