chore(deps): update dependency semver to v6 (#1740)

Author: renovate[bot]

package-lock.json

@@ -45,7 +45,7 @@
     "portfinder": "^1.0.9",
     "schema-utils": "^1.0.0",
     "selfsigned": "^1.9.1",
-    "semver": "^5.6.0",
+    "semver": "^6.0.0",
     "serve-index": "^1.7.2",
     "sockjs": "0.3.19",
     "sockjs-client": "1.3.0",