[DO NOT MERGE] Auto PR to update dependencies of mixer

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[APPROVALNOTIFIER] This PR is NOT APPROVED

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/test all [submit-queue is verifying that this PR is safe to merge]

[codecov[bot]]

Codecov Report

Merging #1506 into master will decrease coverage by 0.02%. The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1506      +/-   ##
==========================================
- Coverage    84.6%   84.57%   -0.03%     
==========================================
  Files         122      122              
  Lines       11997    11997              
==========================================
- Hits        10150    10147       -3     
- Misses       1646     1649       +3     
  Partials      201      201

Impacted Files	Coverage Δ
adapter/prometheus/server.go	89.83% <0%> (-5.09%)	:arrow_down:

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[istio-merge-robot]

Automatic merge from submit-queue.