etl: use == for Map comparison in tests

[dreig]

Use == in tests as it compares the contents of the maps, instead of === which is more strict as requires the two objects to be structurally identical, and may fail depending on how the maps were constructed. https://share.unison-lang.org/@unison/p/code/latest/terms/public/base/latest/data/Map/%3D%3D

The following solution was failing on the second test:

etl.transform : Map Nat [Char] -> Map Char Nat
etl.transform lettersByScore = 
  use Char toLowercase
  fn mp score chars = List.foldLeft (acc ch -> Map.put (toLowercase ch) score acc) mp chars
  Map.foldLeftWithKey fn Map.empty lettersByScore

[github-actions]

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[rlmark]

Thank you @dreig! I'm reopening this and have requested that community contributions be accepted for this repo here.