Bug fixes, alpha support for macOS 27 dev beta

Contributors to this release

Added initial support for macOS 27 Dev Beta release 0. This is very preliminary support. I have verified osxphotos can load a library generated by osxphotos (thanks to an osxphotos user for the test library) but I have not done much testing beyond that. This will likely break with future beta releases as the Photos schema tends to change between beta builds.

Added note to tutorial regarding external volumes and case-sensitivity (thanks @SAY-5)

Fix PhotoKit timeout error (thanks to @realgenekim for the fix)
Fix export speed under certain retry conditions
Fix for FingerprintQuery fails when Photos.sqlite is locked (thanks to @ronkoch2-code for the fix)
Fix setup.py dependencies (thanks to @oPromessa for the fix)