chore(package): update nyc to version 7.0.0

https://greenkeeper.io/

Author: greenkeeperio-bot

package.json

@@ -46,7 +46,7 @@
     "coveralls": "^2.11.9",
     "cpy": "^4.0.1",
     "execa": "^0.4.0",
-    "nyc": "^6.6.1",
+    "nyc": "^7.0.0",
     "path-exists": "^3.0.0",
     "posthtml-bem": "^0.2.2",
     "posthtml-css-modules": "^0.1.0",