support visionOS via CocoaPods

[grachyov]

[!] The platform of the target App visionOS (visionOS 1.0) is not compatible with Kingfisher (7.10.2), which does not support visionOS.

[onevcat]

I believe it just needs to uncomment these https://github.com/onevcat/Kingfisher/blob/master/Kingfisher.podspec#L34-L35

Before an official upgrade can be made, you can also try to fork and edit it temporarily for a while.

[onevcat]

I am having a pod lib linter error, which prevents me from releasing a tag and publish the pod spec.

Seems we need to wait for the next CocoaPods version to get it.

Ref: CocoaPods/CocoaPods#12159 (which is in the master branch, but not yet released.)