remove google-auth dependency for resource detection (#176)

Author: dashpole

opentelemetry-resourcedetector-gcp/setup.cfg

@@ -25,7 +25,6 @@ package_dir=
     =src
 packages=find_namespace:
 install_requires =
-    google-auth ~= 1.22
     opentelemetry-api ~= 1.0
     opentelemetry-sdk ~= 1.0
     requests ~= 2.24