Bump async from 3.2.0 to 3.2.2 in /backend

Bumps [async](https://github.com/caolan/async) from 3.2.0 to 3.2.2.
- [Release notes](https://github.com/caolan/async/releases)
- [Changelog](https://github.com/caolan/async/blob/master/CHANGELOG.md)
- [Commits](https://github.com/caolan/async/compare/v3.2.0...v3.2.2)

---
updated-dependencies:
- dependency-name: async
  dependency-type: direct:production
...

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

backend/package.json

@@ -31,7 +31,7 @@
   "homepage": "",
   "dependencies": {
     "archiver": "^3.1.1",
-    "async": "^3.1.0",
+    "async": "^3.2.2",
     "async-mutex": "^0.3.1",
     "axios": "^0.21.2",
     "bcryptjs": "^2.4.0",