Resize badge to keep consistent with shields.io badges

Related to https://github.com/do-not-theme/do-not-theme.github.io/pull/5

Before

After

I optimized the badge with svgo CLI's default configuration:

svg assets/button/badge.svg

You may have noticed the GNOME badge does not look nice enough. I already have a PR for this: https://github.com/simple-icons/simple-icons/pull/11155.