Use Time.new because JSON.unsafe_load losts fractions of a second and

JSON.unsafe_load with Time object returns String

```
  1) Failure:
JSONCommonInterfaceTest#test_unsafe_load_default_options [/path/to/ruby/test/json/json_common_interface_test.rb:230]:
<2025-09-03 14:28:31.293635 +0200> expected but was
<"2025-09-03 14:28:31 +0200">.
```

Author: hsbt

test/json/json_common_interface_test.rb

@@ -226,8 +226,8 @@ def test_unsafe_load_default_options
     nan_json = '{ "foo": NaN }'
     assert JSON.unsafe_load(nan_json, nil)['foo'].nan?
     assert_equal nil, JSON.unsafe_load(nil, nil)
-    t = Time.now
-    assert_equal t, JSON.unsafe_load(JSON(t))
+    t = Time.new(2025, 9, 3, 14, 50, 0)
+    assert_equal t.to_s, JSON.unsafe_load(JSON(t)).to_s
   end
 
   def test_unsafe_load_with_options