Module 'pip._internal.download' has no attribute 'is_file_url'

pip-compile and the pip-tools package that provide it might sound like actual parts of pip, but they're actually third-party things that abuse the pip internals in ways that are explicitly unsupported and subject to no backward compatibility guarantees.

That means that whenever pip itself gets a new version, there's a pretty decent chance that pip-tools and pip-compile (and anything else that reaches into pip's guts) will abruptly stop working until the pip-tools developers adjust things. When that happens, you have to update pip-tools (if a fix is available), downdate pip (if pip-tools doesn't have a fix available yet), or just stop using pip-tools.