[Feature] Add custom logo for SYL badge using Simple Icons

[aridyckovsky]

Summary

Instead of using the data URI string for the Start Your Lab logo, use a real Simple Icons logo type.

Motivation

The preferred logo consumption for shields on GitHub is Simple Icons, plus a single logo=startyourlab query string extension is preferred to a long URI.

Implementation

Contribute a flat, single-colored version of the branchmark SVG to Simple Icons via these guidelines.