Test on Node.js 18, drop 12 support

[westy92]

No description provided.

[codecov]

Codecov Report

Merging #323 (860034a) into master (af5bb55) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##            master      #323   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           11        11           
  Lines          191       191           
  Branches        28        28           
=========================================
  Hits           191       191           

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[westy92]

https://www.npmjs.com/package/resemblejs

If you need Node.js support and the Canvas dependency fails, try using a previous version of Resemble.js, or npm install --build-from-source.

[westy92]

Automattic/node-canvas#2025

[westy92]

Closing in favor of #329.