build(deps-dev): bump pre-commit from 2.6.0 to 2.7.1 in /backend (#590)

Bumps [pre-commit](https://github.com/pre-commit/pre-commit) from 2.6.0 to 2.7.1.
- [Release notes](https://github.com/pre-commit/pre-commit/releases)
- [Changelog](https://github.com/pre-commit/pre-commit/blob/master/CHANGELOG.md)
- [Commits](pre-commit/pre-commit@v2.6.0...v2.7.1)

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

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

Author: dependabot[bot]

backend/requirements-dev.txt

@@ -1,5 +1,5 @@
 fakeredis==1.4.1
-pre-commit==2.6.0
+pre-commit==2.7.1
 pytest==6.0.1
 pytest-responses==0.4.0
 responses==0.11.0