GUACAMOLE-1765: Switch to firefox browser.

guacamole-common-js/package.json

@@ -2,7 +2,7 @@
   "description": "Dependencies to be installed by maven for running JS tests",
   "devDependencies": {
     "karma": "^6.4.1",
-    "karma-chrome-launcher": "^3.1.1",
+    "karma-firefox-launcher": "^2.1.2",
     "karma-jasmine": "^5.1.0"
   }
 }