Remove calls to PartialFunction.apply, deprecated in 2.12.5

[ghost]

PartialFunction.apply is deprecated in 2.12.5, removed in 2.13.0. So this PR is advance work for the 2.13 build. Error message in 2.13.0-M3 build:

method apply in object PartialFunction is deprecated (since 2.12.5): For converting an ordinary function f to a partial function pf, use val pf: PartialFunction[A, B] = { case x => f(x) }. For creating a new PartialFunction, use an explicit type annotation instead, like in val pf: PartialFunction[Int, String] = { case 1 => "one" }.

Required for #2173

[codecov-io]

Codecov Report

Merging #2188 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master    #2188   +/-   ##
=======================================
  Coverage   94.75%   94.75%           
=======================================
  Files         330      330           
  Lines        5568     5568           
  Branches      201      203    +2     
=======================================
  Hits         5276     5276           
  Misses        292      292

Impacted Files	Coverage Δ
laws/src/main/scala/cats/laws/MonadErrorLaws.scala	100% <100%> (ø)	⬆️
...rc/main/scala/cats/laws/ApplicativeErrorLaws.scala	100% <100%> (ø)	⬆️

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[LukaJCB]

Thanks!