binderhub image: bump to google-cloud-logging v3 (from v1)

Author: consideRatio

helm-chart/images/binderhub/requirements.in

@@ -1,12 +1,18 @@
-# FIXME: google-cloud-logging was pinned to avoid introducing a potentially
-#        breaking change as major version 2 was recently released. See:
-#        https://github.com/googleapis/python-logging/blob/master/UPGRADING.md
-google-cloud-logging==1.*
+# google-cloud-logging is an optional dependency used by mybinder.org-deploy at
+# https://github.com/jupyterhub/mybinder.org-deploy/blob/e47021fe/mybinder/values.yaml#L193-L216.
+#
+# We pin it to avoid introducing a potentially breaking change as major versions
+# are released. See:
+# https://github.com/googleapis/python-logging/blob/master/UPGRADING.md
+#
+google-cloud-logging==3.*
 
-# jupyterhub is pinned to match the JupyterHub Helm chart's
-# version of jupyterhub
+# jupyterhub's major version should be matched with the JupyterHub Helm chart's
+# used version of JupyterHub.
+#
 jupyterhub==1.5.*
 
+# https://github.com/kubernetes-client/python
 kubernetes==9.*
 
 # binderhub's dependencies