Bump sqlfluff from 3.5.0 to 4.0.4 in /src (#4410)

Bumps [sqlfluff](https://github.com/sqlfluff/sqlfluff) from 3.5.0 to 4.0.4.
- [Release notes](https://github.com/sqlfluff/sqlfluff/releases)
- [Changelog](https://github.com/sqlfluff/sqlfluff/blob/main/CHANGELOG.md)
- [Commits](sqlfluff/sqlfluff@3.5.0...4.0.4)

---
updated-dependencies:
- dependency-name: sqlfluff
  dependency-version: 4.0.4
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

src/requirements.txt

@@ -4,4 +4,4 @@ gunicorn==25.0.3
 pytest==9.0.2
 pytest-watch==4.2.0
 pytest-cov==7.0.0
-sqlfluff==3.5.0
+sqlfluff==4.0.4