Yams: replace use of MSVCRT (jpsim#280)

Replace `MSVCRT` with `ucrt`.  There is nothing being used from the
`MSVCRT` module, prefer using `ucrt`.

Author: compnerd

Sources/Yams/Representer.swift

@@ -11,7 +11,7 @@ import CoreFoundation
 #endif
 import Foundation
 #if os(Windows)
-import MSVCRT
+import ucrt
 #endif
 
 public extension Node {