chore(deps): update dependency mocha to v6 (#26)

Author: renovate[bot]

package.json

@@ -114,7 +114,7 @@
     "lnfs-cli": "^2.1.0",
     "lodash": "^4.17.11",
     "mkdirp": "^0.5.1",
-    "mocha": "^5.2.0",
+    "mocha": "^6.1.4",
     "nyc": "^13.1.0",
     "parcel-bundler": "^1.11.0",
     "prettier": "^1.18.2",