Fix color again, for legacy badges (#2782)

Ref: https://github.com/badges/shields/pull/2780#issuecomment-454873296

services/github/github-commits-since.tester.js

@@ -5,11 +5,14 @@ const Joi = require('joi')
 const t = (module.exports = require('../create-service-tester')())
 
 t.create('Commits since')
-  .get('/badges/shields/a0663d8da53fb712472c02665e6ff7547ba945b7.json')
+  .get(
+    '/badges/shields/a0663d8da53fb712472c02665e6ff7547ba945b7.json?style=_shields_test'
+  )
   .expectJSONTypes(
     Joi.object().keys({
       name: Joi.string().regex(/^(commits since){1}[\s\S]+$/),
       value: Joi.string().regex(/^\w+$/),
+      color: 'blue',
     })
   )