CI: Don't run benchmarks

[abhinav]

We don't need to run benchmarks in CI,
especially because it's difficult to get consistent numbers out of it.

We're experimenting with Bencher for
continuous benchmarking.

[codecov]

Codecov Report

Merging #1029 (5ec8927) into master (aea2a50) will not change coverage.
The diff coverage is 100.00%.

❗ Current head 5ec8927 differs from pull request most recent head e2d3bef. Consider uploading reports for the commit e2d3bef to get more accurate results

@@           Coverage Diff           @@
##           master    #1029   +/-   ##
=======================================
  Coverage   98.20%   98.20%           
=======================================
  Files          47       47           
  Lines        2067     2067           
=======================================
  Hits         2030     2030           
  Misses         29       29           
  Partials        8        8           

Impacted Files	Coverage Δ
writer.go	100.00% <100.00%> (ø)

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