npm install fails on M1 MBP

[jkomoros]

Apparently due to gifencoder dependency. Perhaps doesn't work on apple silicon?

[jkomoros]

Automattic/node-canvas#1825

[jkomoros]

npm install --only=prod is a workaround that just skips that gifencoder dependency (but won't allow generating screenshots)

[jkomoros]

Automattic/node-canvas#1733