build(deps): bump flake8 in /.github/workflows/requirements/style (spack#50924)

Bumps [flake8](https://github.com/pycqa/flake8) from 7.2.0 to 7.3.0.
- [Commits](PyCQA/flake8@7.2.0...7.3.0)

---
updated-dependencies:
- dependency-name: flake8
  dependency-version: 7.3.0
  dependency-type: direct:production
  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]

.github/workflows/requirements/style/requirements.txt

@@ -1,6 +1,6 @@
 black==25.1.0
 clingo==5.8.0
-flake8==7.2.0
+flake8==7.3.0
 isort==6.0.1
 mypy==1.16.1
 types-six==1.17.0.20250515