update to go1.16 and add mergify button

[theflyingcodr]

As it says up there, add go1.16 to go.mod and adding mergify status button.

[codecov-commenter]

Codecov Report

Merging #36 (7bc20d7) into master (f0c8b3d) will not change coverage.
The diff coverage is n/a.

❗ Current head 7bc20d7 differs from pull request most recent head 42c35a9. Consider uploading reports for the commit 42c35a9 to get more accurate results

@@           Coverage Diff           @@
##           master      #36   +/-   ##
=======================================
  Coverage   78.58%   78.58%           
=======================================
  Files          18       18           
  Lines        1158     1158           
=======================================
  Hits          910      910           
  Misses        165      165           
  Partials       83       83           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update f0c8b3d...42c35a9. Read the comment docs.