Pass Span instead of Memory

IdentityShroud.Core/Services/DekEncryptionService.cs

@@ -22,7 +22,7 @@ public class DekEncryptionService : IDekEncryptionService
         //     throw new Exception("Key must be 256 bits (32 bytes) for AES‑256‑GCM.");
     }
 
-    public EncryptedDek Encrypt(ReadOnlyMemory<byte> plaintext)
+    public EncryptedDek Encrypt(ReadOnlySpan<byte> plaintext)
     {
         var encryptionKey = ActiveKey;
         byte[] cipher = Encryption.Encrypt(plaintext, encryptionKey.Key);