Bump arrow from 1.0.3 to 1.2.2 in /backend/app

Bumps [arrow](https://github.com/arrow-py/arrow) from 1.0.3 to 1.2.2.
- [Release notes](https://github.com/arrow-py/arrow/releases)
- [Changelog](https://github.com/arrow-py/arrow/blob/master/CHANGELOG.rst)
- [Commits](arrow-py/arrow@1.0.3...1.2.2)

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

Signed-off-by: dependabot[bot] <[email protected]>