fix(package): update yargs to version 15.3.0

Closes #26

Author: greenkeeper[bot]

package.json

@@ -40,7 +40,7 @@
     "recursive-copy": "2.0.10",
     "strip-ansi": "6.0.0",
     "terminate": "2.1.2",
-    "yargs": "15.0.2"
+    "yargs": "15.3.0"
   },
   "devDependencies": {
     "ava": "0.25.0",