Update dependency karma to v6.4.1

Author: renovate[bot]

package-lock.json

@@ -33,7 +33,7 @@
     "@types/node": "^12.11.1",
     "autoprefixer": "^10.4.4",
     "jasmine-core": "~4.0.0",
-    "karma": "~6.3.0",
+    "karma": "6.4.1",
     "karma-chrome-launcher": "~3.1.0",
     "karma-coverage": "~2.1.0",
     "karma-jasmine": "~4.0.0",