chore: remove canvas test

[styfle]

This fixes an issue when a contributor (or GH Actions) runs npm install using Apple Silicon which would fail since there is no precompiled arm64 binary to download for canvas. The error looks like this:

npm ERR! node-pre-gyp http GET https://github.com/Automattic/node-canvas/releases/download/v2.11.2/canvas-v2.11.2-node-v108-darwin-unknown-arm64.tar.gz
npm ERR! node-pre-gyp ERR! install response status 404 Not Found on https://github.com/Automattic/node-canvas/releases/download/v2.11.2/canvas-v2.11.2-node-v108-darwin-unknown-arm64.tar.gz 
npm ERR! node-pre-gyp WARN Pre-built binaries not installable for canvas@2.11.2 and node@18.19.0 (node-v108 ABI, unknown) (falling back to source compile with node-gyp) 

Since we don't have a special case for canvas and it never worked with Vercel deployments, we can remove the test.

It also doesn't decrease code coverage (in fact, I bumped code coverage thresholds just to be sure).

Related

• https://github.com/Automattic/node-canvas/issues/1733
• https://github.com/vercel/vercel/issues/3460

[github-actions[bot]]

:tada: This PR is included in version 0.26.4 :tada:

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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