Add support for Node16 and remove Node10

[somewhatabstract]

Fixes #643 and fixes #642

Includes #669 since I'm comparing against main to trigger the test runs.

[codecov]

Codecov Report

Merging #670 (14be1a5) into main (bccaeb9) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #670   +/-   ##
=======================================
  Coverage   99.81%   99.81%           
=======================================
  Files          30       30           
  Lines         548      548           
  Branches      108      108           
=======================================
  Hits          547      547           
  Misses          1        1           

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