Update dependency karma to v6

Author: renovate[bot]

package.json

@@ -37,7 +37,7 @@
     "codelyzer": "~4.5.0",
     "jasmine-core": "~2.99.1",
     "jasmine-spec-reporter": "~4.2.1",
-    "karma": "~3.1.1",
+    "karma": "~6.4.0",
     "karma-chrome-launcher": "~2.2.0",
     "karma-coverage-istanbul-reporter": "~2.0.1",
     "karma-jasmine": "~1.1.2",