Fix outdated dependencies.

[ariarijp]

Related to #34.

Problem

When I clone this repo and run poetry install, then poetry occurs SolverProblemError.

Steps to reproduce

(.venv) ➜  redash-toolbelt git:(master) poetry install
Installing dependencies from lock file
Warning: The lock file is not up to date with the latest changes in pyproject.toml. You may be getting outdated dependencies. Run update to update them.

  SolverProblemError

  Because redash-toolbelt depends on click (^7.0) which doesn't match any versions, version solving failed.

  at ~/.pyenv/versions/3.9.1/lib/python3.9/site-packages/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