Bumb library version on README file (#40)

* Bumb library version on README file

* Fix compilation problem on old versions

Author: fbenevides

README.md

@@ -48,7 +48,7 @@ source 'https://github.com/CocoaPods/Specs.git'
 platform :ios, '14.0'
 use_frameworks!
 
-pod 'NWWebSocket', '~> 0.5.2'
+pod 'NWWebSocket', '~> 0.5.3'
 ```
 
 Then, run the following command:
@@ -90,7 +90,7 @@ let package = Package(
     ],
     dependencies: [
         .package(url: "https://github.com/pusher/NWWebSocket.git",
-                 .upToNextMajor(from: "0.5.2")),
+                 .upToNextMajor(from: "0.5.3")),
     ],
     targets: [
         .target(

Sources/NWWebSocket/Model/Client/NWWebSocket.swift

@@ -352,7 +352,7 @@ open class NWWebSocket: WebSocketConnection {
         disconnectionWorkItem?.cancel()
 
         disconnectionWorkItem = DispatchWorkItem { [weak self] in
-            guard let self else { return }
+            guard let self = self else { return }
             self.delegate?.webSocketDidDisconnect(connection: self,
                                                   closeCode: closeCode,
                                                   reason: reason)