fix: size calculation for EC keys in Piv

Author: DennisDyallo

Yubico.YubiKey/src/Yubico/YubiKey/Piv/PivEccPublicKey.cs

@@ -231,12 +231,13 @@ private static int GetExpectedSize([DisallowNull] PivAlgorithm? algorithm)
             }
 
             int expectedSize = algorithm.Value.GetPivKeyDefinition().KeyDefinition.LengthInBytes;
-            if (algorithm.Value is PivAlgorithm.EccP256 or PivAlgorithm.EccP384)
+            if (algorithm.Value is PivAlgorithm.EccEd25519 or PivAlgorithm.EccX25519)
             {
-                return (expectedSize * 2) + 1;
+                return expectedSize;
             }
 
-            return expectedSize;
+            return (expectedSize * 2) + 1;
+
         }
     }
 }