GM config to use imagemagick instead

[Henco1]

Received Error: Command failed: gm convert: Coder did not return an image (this is a bug, please report it!) (/tmp/gmmSJZta) [No such file or directory]. when executing image conversion on ubuntu.

I solved this issue by updating const gm = require("gm").subClass({ imageMagick: true });

and then updating sudo vim /etc/ImageMagick-6/policy.xml with <policy domain="coder" rights="read|write" pattern="PDF" />

it would be great if imageMagick: true could be passed into the constructor instead of me having to fork the repo and update the code myself.