new icon: pug (original, plain, line)

[GCHQDeveloper926]

• [x] PR does not match another non-stale PR currently opened
• [x] PR name matches the format new icon: Icon name (versions separated by comma). More details here
• [x] PR's base is the develop branch.
• [x] Your icons are inside a folder as seen here
• [x] SVG matches the standards laid out here
• [x] A new object is added in the devicon.json file at the correct alphabetic position as seen here

**This PR closes #567 **

Link to prove your SVG is correct and up-to-date.

(https://github.com/pugjs/pug-logo/blob/master/SVG/pug-final-logo-_-colour-128.svg)

[GCHQDeveloper926]

First PR into here but hopefully have met all the required points. Do I need to remove the title/formatting from original SVG that I've copied?

[GCHQDeveloper926]

Ok, Ive optimised the original icon and included the suggested plain and original from @Snailedlt . How is it looking now @canaleal - let me know if I need to optimise anything else

[GCHQDeveloper926]

Anything further needed on this?

[GCHQDeveloper926]

Suggestions re newlines resolved, thanks @weh