Add support for Click 8.x

[MarkusH]

Right now, the setup.py pins Click to version 7.x, which makes it impossible to use version 8.x.

Here is the changelog for Click 8.0.0: https://click.palletsprojects.com/en/8.0.x/changes/

[m040601]

Another vote for this one.
We also have click 8 has the "official' click version in Arch Linux.

Please mark it compatible

From

install_requires=[
        "click~=7.0",

to

install_requires=[
        "click>7.0",

Additional question.

Does:

"py-lru-cache~=0.1.4",

has to be "exactly" that version ?

[fabaff]

The missing support for Click > 8 causes issues to build the NixOS packages.

[stonebig]

it would nice now to support click-8.x