Update coveralls to the latest version 🚀 (#17)

package.json

@@ -41,7 +41,7 @@
     "ava": "^0.22.0",
     "camelcase": "^4.0.0",
     "canvas": "^1.6.2",
-    "coveralls": "^2.11.15",
+    "coveralls": "^3.0.0",
     "datauri": "^1.0.5",
     "eslint-config-xo-lukechilds": "^1.0.0",
     "nyc": "^11.0.2",