test: add parentheses to method calls on assignment RHS

Preparation for future grammar simplification that may
require parentheses for method calls with arguments on
the right-hand side of assignments.

Co-authored-by: Claude <noreply@anthropic.com>

test/t/exception.rb

@@ -46,7 +46,7 @@ assert('NameError', '15.2.31') do
     raise NameError.new
   end
 
-  e = NameError.new "msg", "name"
+  e = NameError.new("msg", "name")
   assert_equal "msg", e.message
   assert_equal "name", e.name
 end

test/t/nomethoderror.rb

@@ -9,7 +9,7 @@ assert('NoMethodError', '15.2.32') do
 end
 
 assert('NoMethodError#args', '15.2.32.2.1') do
-  a = NoMethodError.new 'test', :test, [1, 2]
+  a = NoMethodError.new('test', :test, [1, 2])
   assert_equal [1, 2], a.args
 
   assert_nothing_raised do