Fix issues caused by `<|>` being made infixr

[JordanMartinez]

Fix issues caused by switching <|> to be right associative.

[6/8 MixedAssociativityError] .spago/string-parsers/main/src/StringParser/CodeUnits.purs:116:45

  116  anyLetter = lowerCaseChar <|> upperCaseChar <?> "Expected a letter"
                                                   ^^^
  
  Cannot parse an expression that uses operators of the same precedence but mixed associativity:
  
    StringParser.Combinators.(<?>) is infixl
    Control.Alt.(<|>) is infixr
  
  Use parentheses to resolve this ambiguity.

[7/8 MixedAssociativityError] .spago/string-parsers/main/src/StringParser/CodeUnits.purs:120:35

  120  alphaNum = anyLetter <|> anyDigit <?> "Expected a letter or a number"
                                         ^^^
  
  Cannot parse an expression that uses operators of the same precedence but mixed associativity:
  
    StringParser.Combinators.(<?>) is infixl
    Control.Alt.(<|>) is infixr
  
  Use parentheses to resolve this ambiguity.

[8/8 MixedAssociativityError] .spago/string-parsers/main/src/StringParser/Expr.purs:60:15

  60                <?> "operator"
                    ^^^
  
  Cannot parse an expression that uses operators of the same precedence but mixed associativity:
  
    StringParser.Combinators.(<?>) is infixl
    Control.Alt.(<|>) is infixr
  
  Use parentheses to resolve this ambiguity.