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

Author: renovate[bot]

package.json

@@ -36,7 +36,7 @@
     "codelyzer": "^4.0.1",
     "jasmine-core": "~2.8.0",
     "jasmine-spec-reporter": "~4.2.1",
-    "karma": "~2.0.0",
+    "karma": "~6.4.0",
     "karma-chrome-launcher": "~2.2.0",
     "karma-coverage-istanbul-reporter": "^1.2.1",
     "karma-jasmine": "~1.1.0",