Add beta branch support

Author: intitni

Core/Package.swift

@@ -289,6 +289,7 @@ let package = Package(
             name: "UpdateChecker",
             dependencies: [
                 "Sparkle",
+                .product(name: "Preferences", package: "Tool"),
                 .product(name: "Logger", package: "Tool"),
             ]
         ),

Core/Sources/UpdateChecker/UpdateChecker.swift

@@ -1,5 +1,6 @@
-import Sparkle
 import Logger
+import Preferences
+import Sparkle
 
 public final class UpdateChecker {
     let updater: SPUUpdater
@@ -35,3 +36,13 @@ public final class UpdateChecker {
     }
 }
 
+class UpdaterDelegate: NSObject, SPUUpdaterDelegate {
+    func allowedChannels(for updater: SPUUpdater) -> Set<String> {
+        if UserDefaults.shared.value(for: \.installBetaBuilds) {
+            Set(["beta"])
+        } else {
+            []
+        }
+    }
+}
+

Tool/Sources/Preferences/Keys.swift

@@ -93,6 +93,13 @@ public struct UserDefaultPreferenceKeys {
         defaultValue: false,
         key: "ShowHideWidgetShortcutGlobally"
     )
+    
+    // MARK: Update Channel
+    
+    public let installBetaBuilds = PreferenceKey(
+        defaultValue: false,
+        key: "InstallBetaBuilds"
+    )
 }
 
 // MARK: - OpenAI Account Settings