chore(deps): update dependency google-auth to v2.16.0

Author: renovate-bot

.kokoro/requirements.txt

@@ -150,8 +150,9 @@ google-api-core==2.8.2 \
     #   -r requirements.in
     #   google-cloud-core
     #   google-cloud-storage
-google-auth==2.14.1 \
-    --hash=sha256:f5d8701633bebc12e0deea4df8abd8aff31c28b355360597f7f2ee60f2e4d016
+google-auth==2.16.0 \
+    --hash=sha256:5045648c821fb72384cdc0e82cc326df195f113a33049d9b62b74589243d2acc \
+    --hash=sha256:ed7057a101af1146f0554a769930ac9de506aeca4fd5af6543ebe791851a9fbd
     # via
     #   -r requirements.in
     #   gcp-releasetool