Use cats-parse instead of atto for the Maven parser

[fthomas]

The reason for this change is to have less parsing libraries.

[codecov]

Codecov Report

Merging #2275 (ec45673) into master (5b2e2d5) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #2275      +/-   ##
==========================================
+ Coverage   77.95%   77.97%   +0.01%     
==========================================
  Files         135      135              
  Lines        2295     2297       +2     
  Branches       52       50       -2     
==========================================
+ Hits         1789     1791       +2     
  Misses        506      506              

Impacted Files	Coverage Δ
...org/scalasteward/core/buildtool/maven/parser.scala	100.00% <100.00%> (ø)

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