0.7.1 started. fixed secret key serialization excessive size for signing/verifying keys

src/commonMain/kotlin/net/sergeych/crypto2/SigningSecretKey.kt

@@ -30,6 +30,7 @@ class SigningSecretKey(
     override fun seal(message: UByteArray, expiresAt: Instant?): Seal =
         Seal.create(this, message, now(), expiresAt)
 
+    @Transient
     override val id: KeyId = verifyingKey.id
 
     override val label: String