Swift 6 concurrency-safe

[motafan]

public static let shared = AVMediaCache.init() // Class property 'shared' is not concurrency-safe because it is not either conforming to 'Sendable' or isolated to a global actor; this is an error in Swift 6

[cocomanbar]

public static let shared = AVMediaCache.init() // Class property 'shared' is not concurrency-safe because it is not either conforming to 'Sendable' or isolated to a global actor; this is an error in Swift 6

In Swift 6, due to enhanced concurrency checks, you may encounter warnings about class properties shared not being concurrency-safe. This is because it involves shared mutable state. I will be compatible with Swift 6 syntax in the future, but not now, my macOS system is not upgraded. thx~