Accidentally exposed a setter

Author: grynspan

Sources/Testing/Attachments/Images/AttachableImageFormat.swift

@@ -69,7 +69,7 @@ public struct AttachableImageFormat: Sendable {
   /// @Metadata {
   ///   @Available(Swift, introduced: 6.3)
   /// }
-  public var encodingQuality: Float = 1.0
+  public private(set) var encodingQuality: Float = 1.0
 
   package init(kind: Kind, encodingQuality: Float) {
     self.kind = kind