Bump flake8 from 3.8.4 to 7.3.0 in /.github/workflows

Bumps [flake8](https://github.com/pycqa/flake8) from 3.8.4 to 7.3.0.
- [Commits](PyCQA/flake8@3.8.4...7.3.0)

---
updated-dependencies:
- dependency-name: flake8
  dependency-version: 7.3.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/constraints.txt

@@ -1,5 +1,5 @@
 pip==21.0
 pre-commit==2.9.3
 black==20.8b1
-flake8==3.8.4
+flake8==7.3.0
 reorder-python-imports==2.3.6