Update flake8 requirement from ~=6.1 to ~=7.0

Updates the requirements on [flake8](https://github.com/pycqa/flake8) to permit the latest version.
- [Commits](PyCQA/flake8@6.1.0...7.0.0)

---
updated-dependencies:
- dependency-name: flake8
  dependency-type: direct:production
...

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

pyproject.toml

@@ -50,7 +50,7 @@ dynamic = ["version"]
 [project.optional-dependencies]
 tests = [
     "bandit[toml]~=1.7",
-    "flake8~=6.1",
+    "flake8~=7.0",
     "pylint~=3.0",
     "pytest~=7.4",
     "pytest-cov~=4.0",