fix(deps): update dependency yargs to v15 (#484)

Author: renovate[bot]

package.json

@@ -52,7 +52,7 @@
     "git-semver-tags": "3.0.1",
     "semver": "6.3.0",
     "stringify-package": "1.0.1",
-    "yargs": "14.2.2"
+    "yargs": "15.0.2"
   },
   "devDependencies": {
     "chai": "4.2.0",