update google-auth-library to 0.17.2

[chingor13]

No description provided.

[codecov]

Codecov Report

Merging #789 into master will decrease coverage by 0.02%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master     #789      +/-   ##
============================================
- Coverage     78.39%   78.37%   -0.03%     
+ Complexity     1106     1105       -1     
============================================
  Files           198      198              
  Lines          4887     4887              
  Branches        385      385              
============================================
- Hits           3831     3830       -1     
  Misses          887      887              
- Partials        169      170       +1

Impacted Files	Coverage Δ	Complexity Δ
.../java/com/google/api/gax/batching/BatcherImpl.java	97.2% <0%> (-0.7%)	14% <0%> (-1%)

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[chingor13]

Codecov's coverage seems incorrect here

[vam-google]

LGTM

[elharo]

Yes, I don't think codecov is accurate to 4 significant digits. We should probably loosen that check a bit.