chore(deps): update dependency karma to v6 [security] (#884)

Author: renovate-bot

package.json

@@ -58,7 +58,7 @@
     "colors": "1.4.0",
     "gts": "3.1.0",
     "istanbul-instrumenter-loader": "3.0.1",
-    "karma": "5.2.3",
+    "karma": "6.3.14",
     "karma-chrome-launcher": "3.1.0",
     "karma-coverage-istanbul-reporter": "3.0.3",
     "karma-mocha": "2.0.1",