Remove a codepath meant for 3.7.

(We no longer support it.)

Author: Julian

jsonschema/protocols.py

@@ -8,20 +8,14 @@
 from __future__ import annotations
 
 from collections.abc import Mapping
-from typing import TYPE_CHECKING, Any, ClassVar, Iterable
-import sys
-
-# doing these imports with `try ... except ImportError` doesn't pass mypy
-# checking because mypy sees `typing._SpecialForm` and
-# `typing_extensions._SpecialForm` as incompatible
-#
-# see:
-# https://mypy.readthedocs.io/en/stable/runtime_troubles.html#using-new-additions-to-the-typing-module
-# https://github.com/python/mypy/issues/4427
-if sys.version_info >= (3, 8):
-    from typing import Protocol, runtime_checkable
-else:
-    from typing_extensions import Protocol, runtime_checkable
+from typing import (
+    TYPE_CHECKING,
+    Any,
+    ClassVar,
+    Iterable,
+    Protocol,
+    runtime_checkable,
+)
 
 # in order for Sphinx to resolve references accurately from type annotations,
 # it needs to see names like `jsonschema.TypeChecker`