dependency: (deps): bump simplejson from 3.19.2 to 3.19.3 in /backend

Bumps [simplejson](https://github.com/simplejson/simplejson) from 3.19.2 to 3.19.3.
- [Release notes](https://github.com/simplejson/simplejson/releases)
- [Changelog](https://github.com/simplejson/simplejson/blob/master/CHANGES.txt)
- [Commits](simplejson/simplejson@v3.19.2...v3.19.3)

---
updated-dependencies:
- dependency-name: simplejson
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

backend/requirements.txt

@@ -18,7 +18,7 @@ packaging==24.1
 pytz==2024.1
 PyYAML==6.0.2
 requests==2.32.3
-simplejson==3.19.2
+simplejson==3.19.3
 sqlparse==0.5.1
 typing_extensions==4.12.2
 tzdata==2024.1