Switch from using flake8 to using flake8 + ruff

[fabi200123]

This PR contains 2 commits:

• First one adds ruff + flake8 instead of just flake8 for verifying the coding style
• Second commit contains the formatted code from tox -e fmt, plus the fix of changing of the following error:

coriolis git:(switch-to-ruff) tox -e fmt                                     
fmt: commands[0]> ruff check --fix /Users/fabian/Documents/CBSL/coriolis
E741 Ambiguous variable name: `l`
   --> coriolis/osmorphing/base.py:341:26
    |
340 |         add = [p[0] for p in itertools.chain.from_iterable(
341 |                [l for k, l in self._packages.items() if k in k_add])]
    |                          ^
342 |
343 |         # If the second value in the tuple is True, the package must
    |

E741 Ambiguous variable name: `l`
   --> coriolis/osmorphing/base.py:346:29
    |
344 |         # be uninstalled on export
345 |         remove = [p[0] for p in itertools.chain.from_iterable(
346 |                   [l for k, l in self._packages.items()])
    |                             ^
347 |                   if p[1]]
    |

Found 234 errors (232 fixed, 2 remaining).
fmt: exit 1 (0.45 seconds) /Users/fabian/Documents/CBSL/coriolis> ruff check --fix /Users/fabian/Documents/CBSL/coriolis pid=45407
  fmt: FAIL code 1 (0.55=setup[0.10]+cmd[0.45] seconds)
  evaluation failed :( (0.68 seconds)

Changing it to pkgs for k, pkgs in self._packages.items() if k in k_add