Test fix

Author: elsh

Sources/SPMTestSupport/MockTarget.swift

@@ -76,7 +76,7 @@ public struct MockTarget {
         case .binary:
             return try TargetDescription(
                 name: self.name,
-                group: .init(from: self.group as! Decoder),
+                group: .init(self.group),
                 dependencies: self.dependencies.map{ try $0.convert(identityResolver: identityResolver) },
                 path: self.path,
                 url: self.url,