revert 3.7 changes

Author: daniel-sanche

setup.py

@@ -76,7 +76,6 @@
     # TODO(https://github.com/googleapis/google-auth-library-python/issues/1722): `test_aiohttp_requests` depend on
     # aiohttp < 3.10.0 which is a bug. Investigate and remove the pinned aiohttp version.
     "aiohttp < 3.10.0",
-    "mock; python_version < '3.8'",
 ]
 
 extras = {

testing/constraints-3.7.txt

@@ -10,4 +10,4 @@ setuptools==40.3.0
 rsa==3.1.4
 aiohttp==3.6.2
 requests==2.20.0
-pyjwt==2.0
+pyjwt==2.0

tests/transport/aio/test_aiohttp.py

@@ -13,12 +13,7 @@
 # limitations under the License.
 
 import asyncio
-from unittest.mock import Mock, patch
-try:
-    from unittest.mock import AsyncMock
-except ImportError:
-    # Fallback for Python < 3.8
-    from mock import AsyncMock
+from unittest.mock import AsyncMock, Mock, patch
 
 from aioresponses import aioresponses  # type: ignore
 import pytest  # type: ignore

tests_async/oauth2/test_reauth_async.py

@@ -14,11 +14,6 @@
 
 import copy
 from unittest import mock
-try:
-    from unittest.mock import AsyncMock
-except ImportError:
-    # Fallback for Python < 3.8
-    from mock import AsyncMock
 
 import pytest  # type: ignore
 
@@ -27,7 +22,7 @@
 from google.oauth2 import reauth
 
 
-MOCK_REQUEST = AsyncMock(spec=["transport.Request"])
+MOCK_REQUEST = mock.AsyncMock(spec=["transport.Request"])
 CHALLENGES_RESPONSE_TEMPLATE = {
     "status": "CHALLENGE_REQUIRED",
     "sessionId": "123",