Flake8 4.0.0

[g-as]

Flake8 4.x has been released, and since the dependency has been defined here at ^3.5, the update is currently impossible.

There hasn't been any API change, so bumping should be straightforward.

I can open a PR, provided some insight on if you want to keep compatibility with Flake8 3.x.

[sobolevn]

if you want to keep compatibility with Flake8 3.x.

Yes, totally!

I can open a PR

Thank you!

[dycw]

Hi @sobolevn, I think a release is needed, because with

[tool.poetry.dependencies]
python = "^3.6.2"
flake8 = "^4.0.1"
flake8-eradicate = "^1.1.0"

I am running into

❯ poetry update
Updating dependencies
Resolving dependencies... (0.0s)

  SolverProblemError

  Because no versions of flake8-eradicate match >1.1.0,<2.0.0
   and flake8-eradicate (1.1.0) depends on flake8 (>=3.5,<4.0), flake8-eradicate (>=1.1.0,<2.0.0) requires flake8 (>=3.5,<4.0).
  So, because test depends on both flake8 (^4.0.1) and flake8-eradicate (^1.1.0), version solving failed.

  at ~/.poetry/lib/poetry/puzzle/solver.py:241 in _solve
      237│             packages = result.packages
      238│         except OverrideNeeded as e:
      239│             return self.solve_in_compatibility_mode(e.overrides, use_latest=use_latest)
      240│         except SolveFailure as e:
    → 241│             raise SolverProblemError(e)
      242│
      243│         results = dict(
      244│             depth_first_search(
      245│                 PackageNode(self._package, packages), aggregate_package_nodes