Fix numeric colorB (#2780)

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

services/github/github-languages.tester.js

@@ -19,6 +19,16 @@ t.create('top language')
     })
   )
 
+t.create('top language')
+  .get('/top/badges/shields.json?colorB=123&format=_shields_test')
+  .expectJSONTypes(
+    Joi.object().keys({
+      name: 'javascript',
+      value: Joi.string().regex(/^([1-9]?[0-9]\.[0-9]|100\.0)%$/),
+      color: '#123',
+    })
+  )
+
 t.create('top language with empty repository')
   .get('/top/pyvesb/emptyrepo.json')
   .expectJSON({ name: 'language', value: 'none' })