fix: support urllib3<2.0 versions

google/auth/transport/urllib3.py

@@ -40,11 +40,18 @@
         "urllib3 package to use the urllib3 transport."
     ) from caught_exc
 
+from packaging import version  # type: ignore
+
 from google.auth import environment_vars
 from google.auth import exceptions
 from google.auth import transport
 from google.oauth2 import service_account
 
+if version.parse(urllib3.__version__) >= version.parse("2.0.0"):  # pragma: NO COVER
+    RequestMethods = urllib3._request_methods.RequestMethods  # type: ignore
+else:  # pragma: NO COVER
+    RequestMethods = urllib3.request.RequestMethods  # type: ignore
+
 _LOGGER = logging.getLogger(__name__)
 
 
@@ -179,7 +186,7 @@ def _make_mutual_tls_http(cert, key):
     return http
 
 
-class AuthorizedHttp(urllib3._request_methods.RequestMethods):  # type: ignore
+class AuthorizedHttp(RequestMethods):  # type: ignore
     """A urllib3 HTTP class with credentials.
 
     This class is used to perform requests to API endpoints that require

setup.py

@@ -25,7 +25,6 @@
     # rsa==4.5 is the last version to support 2.7
     # https://github.com/sybrenstuvel/python-rsa/issues/152#issuecomment-643470233
     "rsa>=3.1.4,<5",
-    "urllib3>=2.0.5",
 )
 
 extras = {

testing/constraints-3.10.txt

@@ -0,0 +1 @@
+urllib3<2.0.0

testing/constraints-3.11.txt

@@ -0,0 +1 @@
+urllib3>2.0.0