Move support to node 16 and npm 8

[bcomnes]

Fix tests for newer versions of node and npm, and also bump engines to the latest versions of node and npm. YMMV with older versions, though nothing specifically will break with this change other than a warning.

[codecov-commenter]

Codecov Report

Merging #85 (7d19dd4) into master (8e72b7c) will increase coverage by 4.09%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master      #85      +/-   ##
==========================================
+ Coverage   92.66%   96.75%   +4.09%     
==========================================
  Files          23       23              
  Lines         477     1973    +1496     
==========================================
+ Hits          442     1909    +1467     
- Misses         35       64      +29     

Flag	Coverage Δ
macos-latest-18	96.56% <ø> (?)
ubuntu-latest-12	?
ubuntu-latest-14	?
ubuntu-latest-18	96.15% <ø> (?)
windows-latest-12	?
windows-latest-14	?
windows-latest-18	96.22% <ø> (?)

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Impacted Files	Coverage Δ
bin/common/parse-cli-args.js	92.82% <0.00%> (-0.43%)	⬇️
lib/spawn.js	100.00% <0.00%> (ø)
bin/run-p/help.js	100.00% <0.00%> (ø)
bin/run-s/help.js	100.00% <0.00%> (ø)
bin/run-p/index.js	100.00% <0.00%> (ø)
bin/run-s/index.js	100.00% <0.00%> (ø)
lib/match-tasks.js	100.00% <0.00%> (ø)
lib/spawn-posix.js	100.00% <0.00%> (ø)
lib/spawn-win32.js	100.00% <0.00%> (ø)
bin/common/version.js	100.00% <0.00%> (ø)
... and 13 more

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