Update dependency yargs to v15.4.0

Author: renovate-bot

package.json

@@ -49,6 +49,6 @@
     "mocha": "8.0.1",
     "uglifyjs-webpack-plugin": "1.3.0",
     "webpack": "3.12.0",
-    "yargs": "15.3.1"
+    "yargs": "15.4.0"
   }
 }