deps: pin heif-image-plugin to version 0.5.1

[neobooru]

Not sure if this really matters, but it fixes a pip warning. uploadcare/heif-image-plugin@cc55068

• Maybe replace heif-image-plugin with pi-heif as it is more up to date
• Update pillow-avif-plugin so that it works with a newer Pillow
• Lock Pillow version range to something, because now it might randomly break with any avif/heif packages
• Check alpine compatibility with aforementioned packages (specifically the libavif and libheif package versions)

[neobooru]

This might also fix the Failed building wheel for pycryptodomex error that has been popping up in the github runner log.

E: pillow-avif-plugin can't be removed without breaking something. Actually the whole avif/heif landscape is a minefield in python. Maybe first get a working lockfile before changing anything here. Additionally we should probably not install the packages from the alpine repository, as this makes it easier to get out of sync.