Numeric colors weren't properly being handled by `makeBadge` after #2742.
Since this function really does not need to be accepting colors as strings, rather than make the function more lenient to work with Scoutcamp, I coerced the types of the colors on the way in.
Two tests cover the functionality in the modern service. I don't feel strongly that the legacy version needs coverage at this point, though I've added one for the moment on the github languages badge where this manifested.
Fix#2778
