Add svgo to devDependencies and avoid removing viewBox

[dcroote]

I thought this would help per the instructions in CONTRIBUTING.md. Note I didn't add svgo-viewbox because whenever I used it with an Inkscape image it would botch the size / viewBox. Instead, adding removeViewBox: false as an override of svgo via the svgo.config.mjs file (long complaint thread here) appears to work well.

[duerrsimon]

Thanks for the pull request. I am against merging it now since it just adds the dev dependency and I don't think many submitters actually clone the repo.
I plan to add a better pipeline that will process uploaded icons consistently removing also illustrator classes (there are a few offenders among the current icons).

[dcroote]

I guess I don't know how your current or proposed processing pipeline is/will be implemented, but having svgo as a devDependency (along with the config file that prevents removal of the viewBox) would open up options to use it within a GitHub Actions workflow.