Fix tests on Node 16

[voxpelli]

Fixes #116 and also fixes failing tests in the standard repo, see: https://github.com/standard/standard/pull/1703

Basically the installed canvas version doesn't compile on Node 16 and it is used by svg2img, which is used by @bubblewrap/core, which in turn is used by @bubblewrap/cli.

Updating @bubblewrap/cli to the latest and greatest version triggers canvas to also be updated to a newer version.

Collateral damage: Started using the npm 7 package-lock format.