test: Run with Node.js 20

[eps1lon]

Current Node.js release that will go into LTS next month

[MatanBobi]

This was already done as part of #1255 which is merged to alpha,
is there any specific reason to have another pr?

[eps1lon]

To have it in main. #1255 also drops support for Node.js 14 which I don't want to do. We can package that with actual features but I see no reason releasing a Major with just Node.js 14 support dropped. That seems kind of boring.

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[codecov]

Codecov Report

Merging #1263 (5d14849) into main (07f5999) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##              main     #1263   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           24        24           
  Lines         1038      1038           
  Branches       351       351           
=========================================
  Hits          1038      1038           

Flag	Coverage Δ
node-14	100.00% <ø> (ø)
node-16	100.00% <ø> (ø)
node-18	100.00% <ø> (ø)
node-20	100.00% <ø> (?)

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