Fix scope option

[euanlau]

Google::Auth::Credentials initialization expects scope, not scopes as an option.

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[codecov-io]

Codecov Report

Merging #132 into master will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #132   +/-   ##
=======================================
  Coverage   99.35%   99.35%           
=======================================
  Files          19       19           
  Lines        2029     2029           
=======================================
  Hits         2016     2016           
  Misses         13       13

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[jbolinger]

@euanlau are you able to sign the CLA so that we can take a look at this?

[euanlau]

@jbolinger just signed it. thanks!

[googlebot]

CLAs look good, thanks!

[jbolinger]

@euanlau looks good. Thanks for catching this!

[euanlau]

any update on this?

[jbolinger]

@euanlau thanks for fixing this!