fix: package.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-AJV-584908
- https://snyk.io/vuln/SNYK-JS-ANSIREGEX-1583908
- https://snyk.io/vuln/SNYK-JS-ENGINEIO-1056749
- https://snyk.io/vuln/SNYK-JS-ENGINEIO-3136336
- https://snyk.io/vuln/SNYK-JS-GLOBPARENT-1016905
- https://snyk.io/vuln/SNYK-JS-ISTANBULREPORTS-2328088
- https://snyk.io/vuln/SNYK-JS-KARMA-2395349
- https://snyk.io/vuln/SNYK-JS-KARMA-2396325
- https://snyk.io/vuln/SNYK-JS-LOG4JS-2348757
- https://snyk.io/vuln/SNYK-JS-SOCKETIO-1024859
- https://snyk.io/vuln/SNYK-JS-SOCKETIOPARSER-1056752
- https://snyk.io/vuln/SNYK-JS-SOCKETIOPARSER-3091012
- https://snyk.io/vuln/SNYK-JS-TRIMNEWLINES-1298042
- https://snyk.io/vuln/SNYK-JS-WS-1296835
- https://snyk.io/vuln/SNYK-JS-XMLHTTPREQUESTSSL-1082936
- https://snyk.io/vuln/SNYK-JS-XMLHTTPREQUESTSSL-1255647
- https://snyk.io/vuln/npm:eslint:20180222

package.json

@@ -63,17 +63,17 @@
     "codecov": "^3.0.4",
     "coveralls": "^3.0.2",
     "function-bind": "^1.0.2",
-    "karma": "^3.0.0",
+    "karma": "^6.3.16",
     "karma-browserify": "^5.0.1",
     "karma-cli": "^1.0.0",
-    "karma-coverage": "^1.0.0",
+    "karma-coverage": "^2.0.2",
     "karma-phantomjs-launcher": "^1.0.0",
     "karma-tap": "^3.0.1",
-    "nyc": "^14.1.1",
+    "nyc": "^15.0.0",
     "phantomjs-prebuilt": "^2.1.3",
     "rimraf": "^2.2.8",
     "server-destroy": "^1.0.1",
-    "standard": "^9.0.0",
+    "standard": "^11.0.0",
     "tape": "^4.6.0",
     "taper": "^0.5.0"
   },