Use Dictionary.sorted(by:)

Co-Authored-By: Dan Zheng <[email protected]>

Author: bgogul

Sources/TensorFlow/Core/LazyTensorOperation.swift

@@ -682,7 +682,7 @@ extension LazyTensor: CustomStringConvertible {
 
 extension LazyTensorOperation: CustomStringConvertible {
     public var description: String {
-        let attrsDesc = attrs.keys.sorted(by: <).map { "\($0): \(attrs[$0]!)" }
+        let attrsDesc = attrs.sorted(by: { $0.key < $1.key }).map { "\($0): \($1)" }
         let inputsDesc = inputs.map { (input: Input) -> String in
             switch input {
             case Input.single(let lazyTensor):