Update dependency karma to v6 [SECURITY]

Author: renovate-bot

package.json

@@ -62,7 +62,7 @@
     "history": "^3.0.0",
     "isparta": "^4.0.0",
     "isparta-loader": "^2.0.0",
-    "karma": "^1.4.1",
+    "karma": "^6.0.0",
     "karma-coverage": "^1.1.1",
     "karma-firefox-launcher": "^1.0.0",
     "karma-mocha": "^1.3.0",