Made the image method in channel header loader open (#595)

Author: martinmitrevski

CHANGELOG.md

@@ -5,6 +5,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 ### 🔄 Changed
 - Improved subtitle info in pinned messages view [#594](https://github.com/GetStream/stream-chat-swiftui/pull/594)
+- The `image(for channel: ChatChannel)` in `ChannelHeaderLoader` is now open [#595](https://github.com/GetStream/stream-chat-swiftui/pull/595) 
 
 ### 🐞 Fixed
 - Typing users did not update reliably in the message list [#591](https://github.com/GetStream/stream-chat-swiftui/pull/591)

Sources/StreamChatSwiftUI/ChatChannelList/ChannelHeaderLoader.swift

@@ -44,7 +44,7 @@ open class ChannelHeaderLoader: ObservableObject {
     /// If the image is not downloaded, placeholder is returned.
     /// - Parameter channel: the provided channel.
     /// - Returns: the available image.
-    public func image(for channel: ChatChannel) -> UIImage {
+    open func image(for channel: ChatChannel) -> UIImage {
         if let image = loadedImages[channel.cid] {
             return image
         }