chore(deps): bump qs from 6.15.0 to 6.15.2 in /backend (#1161)

Bumps [qs](https://github.com/ljharb/qs) from 6.15.0 to 6.15.2.
- [Changelog](https://github.com/ljharb/qs/blob/main/CHANGELOG.md)
- [Commits](https://github.com/ljharb/qs/compare/v6.15.0...v6.15.2)

---
updated-dependencies:
- dependency-name: qs
  dependency-version: 6.15.2
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

backend/package-lock.json

@@ -10,7 +10,6 @@
       "hasInstallScript": true,
       "license": "SEE LICENSE IN LICENSE",
       "dependencies": {
-        "@aws-sdk/client-s3": "3.1051.0",
         "axios": "^1.15.0",
         "bcrypt": "^6.0.0",
         "better-sqlite3": "^12.6.2",
@@ -5984,9 +5983,9 @@
       }
     },
     "node_modules/qs": {
-      "version": "6.15.0",
-      "resolved": "https://registry.npmjs.org/qs/-/qs-6.15.0.tgz",
-      "integrity": "sha512-mAZTtNCeetKMH+pSjrb76NAM8V9a05I9aBZOHztWy/UqcJdQYNsf59vrRKWnojAT9Y+GbIvoTBC++CPHqpDBhQ==",
+      "version": "6.15.2",
+      "resolved": "https://registry.npmjs.org/qs/-/qs-6.15.2.tgz",
+      "integrity": "sha512-Rzq0KEyX/w/tEybncDgdkZrJgVUsUMk3xjh3t5bv3S1HTAtg+uOYt72+ZfwiQwKdysThkTBdL/rTi6HDmX9Ddw==",
       "license": "BSD-3-Clause",
       "dependencies": {
         "side-channel": "^1.1.0"