fix(deps): update dependency yargs to v15 (#222)

Author: renovate-bot

asset/snippets/package.json

@@ -18,7 +18,7 @@
     "@google-cloud/asset": "^1.4.2",
     "@google-cloud/storage": "^4.0.0",
     "uuid": "^3.3.2",
-    "yargs": "^14.0.0"
+    "yargs": "^15.0.0"
   },
   "devDependencies": {
     "chai": "^4.2.0",