correct .from_format() tz hint to match the wrapped .datetime() hint

Author: altendky

pendulum/__init__.py

@@ -252,7 +252,7 @@ def yesterday(tz="local"):  # type: (Union[str, _Timezone]) -> DateTime
 
 def from_format(
     string, fmt, tz=UTC, locale=None,  # noqa
-):  # type: (str, str, Union[str, _Timezone], Optional[str]) -> DateTime
+):  # type: (str, str, Optional[Union[str, float, _Timezone]], Optional[str]) -> DateTime
     """
     Creates a DateTime instance from a specific format.
     """