chore(package): update nyc to version 8.1.0

https://greenkeeper.io/

Author: greenkeeperio-bot

package.json

@@ -31,7 +31,7 @@
     "eslint": "^3.5.0",
     "eslint-config-punchcard": "^1.0.1",
     "ghooks": "^1.3.2",
-    "nyc": "^6.6.1",
+    "nyc": "^8.1.0",
     "punchcard-commit-msg": "^1.0.0",
     "punchcard-semantic-release": "^2.0.1",
     "punchcard-shared-tests": "^1.0.0",