[ruby/timeout] updated tests

ruby/timeout@c6d121aa18

Author: Cosmicoppai

test/test_timeout.rb

@@ -26,7 +26,7 @@ def test_allows_zero_seconds
   end
 
   def test_allows_nil_seconds
-    assert_raise(ArgumentError) do
+    assert_nothing_raised do
       assert_equal :ok, Timeout.timeout(nil){:ok}
     end
   end