[ruby/prism] Enable ParametersSignatureTest on TruffleRuby

https://github.com/ruby/prism/commit/c7a7af1eac

test/prism/parameters_signature_test.rb

@@ -2,7 +2,7 @@
 
 require_relative "test_helper"
 
-return if RUBY_VERSION < "3.2" || RUBY_ENGINE == "truffleruby"
+return if RUBY_VERSION < "3.2"
 
 module Prism
   class ParametersSignatureTest < TestCase
@@ -55,6 +55,8 @@ module Prism
     end
 
     def test_key_ordering
+      omit("TruffleRuby returns keys in order they were declared") if RUBY_ENGINE == "truffleruby"
+
       assert_parameters([[:keyreq, :a], [:keyreq, :b], [:key, :c], [:key, :d]], "a:, c: 1, b:, d: 2")
     end