Bump @types/yargs in package.json

Author: firecow

package-lock.json

@@ -36,7 +36,7 @@
     "@types/pretty-hrtime": "1.x",
     "@types/shelljs": "0.x",
     "@types/yaml": "1.x",
-    "@types/yargs": "13.x",
+    "@types/yargs": "15.x",
     "pkg": "4.x",
     "source-map-support": "0.x",
     "tslint": "5.x",