perceptuallyCompare function has seemingly incorrect operating system check version?

[msmollin]

Describe the bug
While taking a look at how the library implements fuzzy image match comparison, I noticed that the perceptual comparison function is using CILabDeltaE which per Apple's documentation is only available on iOS 13.0+, tvOS 13.0+, and macOS 10.15+.

However the availability annotations here and here declare earlier OS versions. The reason this doesn't fail to compile is CoreImage using a string-based API for setting up filters makes it impossible to check this at build time (yay objective-c APIs).

I suspect this would cause at best a runtime warning, or at worst a crash, but I don't have my environment setup to test this.

Also as a note the two availability annotations declare different iOS versions, which seems a little disorganized.