build: adjust browserstack version

Changes the Browserstack version in an attempt to fix the CI.

Author: crisbeto

package.json

@@ -132,8 +132,8 @@
     "jasmine": "^3.5.0",
     "jasmine-core": "^3.5.0",
     "kagekiri": "^1.0.18",
-    "karma": "^4.4.1",
-    "karma-browserstack-launcher": "^1.3.0",
+    "karma": "^5.2.3",
+    "karma-browserstack-launcher": "1.6.0",
     "karma-chrome-launcher": "^3.1.0",
     "karma-firefox-launcher": "^2.0.0",
     "karma-jasmine": "^4.0.1",