chore: Update semver to the latest version 🚀 (#537)

Author: greenkeeper[bot]

package-lock.json

@@ -48,7 +48,7 @@
   "dependencies": {
     "is-utf8": "^0.2.1",
     "minimatch": "^3.0.4",
-    "semver": "^5.6.0",
+    "semver": "^6.0.0",
     "tmp": "0.1.0",
     "xml2js": "^0.4.19"
   },