Bump prospector from 1.11.0 to 1.12.0 in /backend (#73)

Bumps [prospector](https://github.com/PyCQA/prospector) from 1.11.0 to 1.12.0.
- [Release notes](https://github.com/PyCQA/prospector/releases)
- [Changelog](https://github.com/prospector-dev/prospector/blob/master/CHANGELOG.rst)
- [Commits](prospector-dev/prospector@v1.11.0...v1.12.0)

---
updated-dependencies:
- dependency-name: prospector
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]