[ruby/strscan] test: don't omit "(...)" for method calls that have at least one argument

ruby/strscan@dddae9c99a

Author: kou

test/strscan/test_ractor.rb

@@ -3,7 +3,7 @@
 
 class TestStringScannerRactor < Test::Unit::TestCase
   def setup
-    omit "Ractor not defined" unless defined? Ractor
+    omit("Ractor not defined") unless defined? Ractor
   end
 
   def test_ractor