remove useless [unowned self]

[Akhrameev]

as closures are @noescape by default and don't retain 'self' since Swift version 3

More info: https://stackoverflow.com/questions/38141298/lazy-initialisation-and-retain-cycle https://github.com/apple/swift-evolution/blob/main/proposals/0103-make-noescape-default.md https://michael-kiley.medium.com/why-your-lazy-vars-arent-creating-strong-reference-cycles-in-ios-d512ff2c9403