ALEFix is incompatible with isort < 5.7.0

[jmsanders]

isort didn't introduce the --filename flag until 5.7.0:

• https://github.com/PyCQA/isort/releases/tag/5.7.0
• Passing filename / extension when using stdin to support .pyi files w/ black PyCQA/isort#1596

#3815 introduces --filename which makes fixing incompatible with isort < 5.7.0

Perhaps ale should conditionally add the --filename flag based on the detected version of isort?

[hsanson]

@jmsanders appreciated if you can verify this PR works for you: #3942

[jmsanders]

Yep - works for me! Thanks for the quick fix!