build: bump sqlfluff from 3.1.1 to 3.3.1 in /back

Bumps [sqlfluff](https://github.com/sqlfluff/sqlfluff) from 3.1.1 to 3.3.1.
- [Release notes](https://github.com/sqlfluff/sqlfluff/releases)
- [Changelog](https://github.com/sqlfluff/sqlfluff/blob/main/CHANGELOG.md)
- [Commits](sqlfluff/sqlfluff@3.1.1...3.3.1)

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

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

back/requirements/test.txt

@@ -7,5 +7,5 @@ freezegun==1.5.1
 ruff==0.9.4
 pytest==8.3.4
 pytest-django==4.9.0
-sqlfluff==3.1.1
+sqlfluff==3.3.1
 requests-mock==1.12.1