Pin sinon version to be under v2.0.0

(cherry picked from commit 20447f28)

package.json

@@ -37,7 +37,7 @@
     "pa11y": "4.0.1",
     "pa11y-reporter-json-oldnode": "1.0.0",
     "plato": "1.2.2",
-    "sinon": "1.17.3 || >1.17.4",
+    "sinon": "1.17.3 || >1.17.4 <2.0.0",
     "squirejs": "^0.1.0"
   }
 }