Add email scope to GCP provided credential refresh

[axelsteingrimsson]

This would fix the issue described in: #54

This is similar to the PR to fix the issue with refreshing the service account token, except this is specifically targeted at addressing service account tokens that are authenticated using RBAC.

The issue is essentially that if the service account that is making a request to the Kubernetes API server and the request is authenticated using RBAC, then the access token will be invalid because it isn't signed by an email. By passing the "https://www.googleapis.com/auth/userinfo.email" when creating the credentials it will generate an access token that can be authenticated using RBAC.

[codecov-io]

Codecov Report

Merging #110 into master will not change coverage.
The diff coverage is 0%.

@@           Coverage Diff           @@
##           master     #110   +/-   ##
=======================================
  Coverage   92.04%   92.04%           
=======================================
  Files          13       13           
  Lines        1182     1182           
=======================================
  Hits         1088     1088           
  Misses         94       94

Impacted Files	Coverage Δ
config/kube_config.py	84.24% <0%> (ø)	⬆️

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[micw523]

/lgtm

[axelsteingrimsson]

Hey there @mbohlool and @yliaog, (sorry for the ping) it's no big rush, but would you guys mind taking a look at this if you have any time soon? :)

[yliaog]

thanks for the pr. so you have tested it manually that it works, right? just want to double confirm.

[axelsteingrimsson]

Yes, we've been running a patched version of this client with this change for the past few months in production and we haven't seen any adverse behaviour.

[yliaog]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: axelsteingrimsson, yliaog

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