fix(deps): update dependency @hello.nrfcloud.com/proto to v15.2.0

Author: renovate[bot]

package-lock.json

@@ -110,7 +110,7 @@
     "@hello.nrfcloud.com/certificate-helpers": "1.0.0",
     "@hello.nrfcloud.com/lambda-helpers": "2.0.18",
     "@hello.nrfcloud.com/nrfcloud-api-helpers": "5.3.58",
-    "@hello.nrfcloud.com/proto": "15.1.0",
+    "@hello.nrfcloud.com/proto": "15.2.0",
     "@hello.nrfcloud.com/proto-map": "16.1.3",
     "@middy/core": "5.4.7",
     "@middy/input-output-logger": "5.4.7",