Fix tick delta type handling

## `FrozenDateTimeFactory.tick`
The `delta` argument is capable of handling `float`s. In previous versions of
freezgun, the `.pyi` type annotations were correctly reflecting that. For some
reason, when moving the type annotations into the `.py` file, this information
got lost.

Further, checking for `isinstance(delta, numbers.Real)` is probably not what
was intended as `fraction.Fraction` is a subclass of `Real`, but will cause an
error when passed into `datetime.timedelta(seconds=delta)`.

## `StepTickTimeFactory.tick`
The same issue with the type hint applies here.

Fruther, passing an integer/float `delta` would lead to that number being added
to the frozen `datetime.datetime`, which is not a valid operation
(`TypeError: unsupported operand type(s) for +: 'datetime.datetime' and 'int'`).

freezegun/api.py

@@ -531,8 +531,8 @@ def __init__(self, time_to_freeze: datetime.datetime):
     def __call__(self) -> datetime.datetime:
         return self.time_to_freeze
 
-    def tick(self, delta: Union[datetime.timedelta, int]=datetime.timedelta(seconds=1)) -> datetime.datetime:
-        if isinstance(delta, numbers.Real):
+    def tick(self, delta: Union[datetime.timedelta, float]=datetime.timedelta(seconds=1)) -> datetime.datetime:
+        if isinstance(delta, float):
             # noinspection PyTypeChecker
             self.time_to_freeze += datetime.timedelta(seconds=delta)
         else:
@@ -557,9 +557,11 @@ def __call__(self) -> datetime.datetime:
         self.tick()
         return return_time
 
-    def tick(self, delta: Union[datetime.timedelta, int, None]=None) -> datetime.datetime:
+    def tick(self, delta: Union[datetime.timedelta, float, None]=None) -> datetime.datetime:
         if not delta:
             delta = datetime.timedelta(seconds=self.step_width)
+        elif isinstance(delta, float):
+            delta = datetime.timedelta(seconds=delta)
         self.time_to_freeze += delta  # type: ignore
         return self.time_to_freeze