Handle callable staticmethods (py3.10);

Up to python 3.10, staticmethods were not callable - so they were skipped by the condition.
Since python 3.10, staticmethods ARE callable - so adding the `isinstance(v, staticmethod)`
to the same `if` statement would consistently handle staticmethods across python
versions <=3.9 and >= 3.10.
This solves for:
```
self = <tests.test_datetimes.Tester object at 0x1073dc5e0>

    def test_class_decorator_respects_staticmethod(self):
>       assert self.helper() == datetime.date(2012, 1, 14)

tests/test_datetimes.py:453:
...
>               result = func(*args, **kwargs)
E               TypeError: Tester.helper() takes 0 positional arguments but 1 was given

freezegun/api.py:809: TypeError
```

freezegun/api.py

@@ -619,7 +619,7 @@ def tearDown(*args, **kwargs):
                         continue
                     seen.add(attr)
 
-                    if not callable(attr_value) or inspect.isclass(attr_value):
+                    if not callable(attr_value) or inspect.isclass(attr_value) or isinstance(attr_value, staticmethod):
                         continue
 
                     try: