Fix bad imports from typing_extensions

Author: jg-rp

liquid/builtin/loaders/mixins.py

@@ -10,8 +10,7 @@
 from typing import Callable
 from typing import Mapping
 from typing import Optional
-
-from typing_extensions import Protocol
+from typing import Protocol
 
 from liquid.utils import LRUCache
 from liquid.utils import ThreadSafeLRUCache

liquid/messages.py

@@ -12,10 +12,10 @@
 from typing import Iterable
 from typing import Iterator
 from typing import NamedTuple
+from typing import Protocol
 from typing import Union
 
 from babel.messages import Catalog
-from typing_extensions import Protocol
 
 from .builtin.expressions import Filter
 from .builtin.expressions import FilteredExpression