feat(auth): Implement PEP 0810 lazy loading in transport

Author: hebaalazzeh

packages/google-auth/google/auth/transport/__init__.py

@@ -24,6 +24,18 @@
 for the return value of :class:`Request`.
 """
 
+__lazy_modules__ = {
+    f"{__name__}._aiohttp_requests",
+    f"{__name__}._custom_tls_signer",
+    f"{__name__}._http_client",
+    f"{__name__}._mtls_helper",
+    f"{__name__}._requests_base",
+    f"{__name__}.grpc",
+    f"{__name__}.mtls",
+    f"{__name__}.requests",
+    f"{__name__}.urllib3",
+}
+
 import abc
 import http.client as http_client