Bump to go 1.17

[zix99]

Initial benchmarks show the callsite improvements are speding up rare by a few percentage points. Will post some benchmarks soon.

Histogram benchmark (1.5 GB of logs):
go 1.16: 23s real; 1m17s user time
go 1.17: 20s real; 1m7s user time

About a 12% savings on user-time at a high level.

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[codecov-commenter]

Codecov Report

Merging #60 (0b82655) into master (2f41793) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #60   +/-   ##
=======================================
  Coverage   82.67%   82.67%           
=======================================
  Files          74       74           
  Lines        2806     2806           
=======================================
  Hits         2320     2320           
  Misses        352      352           
  Partials      134      134           

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