build(deps): bump ws from 8.18.0 to 8.21.0 in /apps/backend-docker

Bumps [ws](https://github.com/websockets/ws) from 8.18.0 to 8.21.0.
- [Release notes](https://github.com/websockets/ws/releases)
- [Commits](websockets/ws@8.18.0...8.21.0)

---
updated-dependencies:
- dependency-name: ws
  dependency-version: 8.21.0
  dependency-type: direct:production
...

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

Author: dependabot[bot]

apps/backend-docker/package.json

@@ -41,7 +41,7 @@
     "graphql-yoga": "3.9.1",
     "ioredis": "5.4.1",
     "next-auth": "4.24.14",
-    "ws": "8.18.0"
+    "ws": "8.21.0"
   },
   "devDependencies": {
     "@cypress/code-coverage": "~3.14.6",