build(deps): bump mqtt from 5.14.1 to 5.15.0

Bumps [mqtt](https://github.com/mqttjs/MQTT.js) from 5.14.1 to 5.15.0.
- [Release notes](https://github.com/mqttjs/MQTT.js/releases)
- [Changelog](https://github.com/mqttjs/MQTT.js/blob/main/CHANGELOG.md)
- [Commits](mqttjs/MQTT.js@v5.14.1...v5.15.0)

---
updated-dependencies:
- dependency-name: mqtt
  dependency-version: 5.15.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

package-lock.json

@@ -9,7 +9,7 @@
     "chartkick": "^5.0.1",
     "date-fns": "^4.1.0",
     "esbuild": "^0.27.2",
-    "mqtt": "^5.14.1",
+    "mqtt": "^5.15.0",
     "petite-vue": "^0.4.1",
     "vanilla-nested": "^1.7.1"
   },