FIX: screenshot functions no longer working

[AntoineTheb]

Quick description

scil_screenshot_* scripts were broken because of a fix in Pillow. See: https://stackoverflow.com/questions/76616042/attributeerror-module-pil-image-has-no-attribute-antialias

Replaced ANTIALIAS with LANCZOS, now they work.

Type of change

Check the relevant options.

• [X] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] This change requires a documentation update

Provide data, screenshots, command line to test (if relevant)

...

Checklist

• [X] My code follows the style guidelines of this project (run autopep8)
• [X] I added relevant citations to scripts, modules and functions docstrings and descriptions
• [X] I have performed a self-review of my code
• [X] I have commented my code, particularly in hard-to-understand areas
• [ ] ~I have made corresponding changes to the documentation~
• [ ] ~My changes generate no new warnings~
• [ ] ~I moved all functions from the script file (except the argparser and main) to scilpy modules~
• [X] I have added tests that prove my fix is effective or that my feature works
• [X] New and existing unit tests pass locally with my changes