fix(deps): update dependency @googleapis/iam to v15 (#1772)

Co-authored-by: Daniel Bankhead <[email protected]>

Author: renovate-bot

samples/package.json

@@ -14,7 +14,7 @@
   "license": "Apache-2.0",
   "dependencies": {
     "@google-cloud/storage": "^7.0.0",
-    "@googleapis/iam": "^14.0.0",
+    "@googleapis/iam": "^15.0.0",
     "google-auth-library": "^9.6.3",
     "node-fetch": "^2.3.0",
     "opn": "^5.3.0",