6.0.0

• removed usage of deprecated license_file option for license_files
• fixed flake8 usage in pre-commit
• the module is now available on conda (closes #170)
• MSS: the implementation is now thread-safe on all OSes (fixes #169)
• Linux: better handling of the Xrandr extension (fixes #168)
• tests: fixed a random bug on test_grab_with_tuple_percents() (fixes #142)