build: Update karma to 3.1.4

This fixes the bug where HeadlessChrome was always shown as
version 0.0.0 in the console output, which makes it rather
difficult to debug which Chrome version is installed.

Upstream karma-runner/karma#2762,
which updates the ua-parser library to a version that fixes
that bug.

Change-Id: I0b7fe7f8a90649592c4d31fb3055cdc9e8d34814

package.json

@@ -20,7 +20,7 @@
     "grunt-karma": "3.0.0",
     "grunt-stylelint": "0.10.1",
     "grunt-svgmin": "5.0.0",
-    "karma": "3.0.0",
+    "karma": "3.1.4",
     "karma-chrome-launcher": "2.2.0",
     "karma-firefox-launcher": "1.1.0",
     "karma-mocha-reporter": "2.2.5",