seal now allows up to 45s in future to tolerate some time difference

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

@@ -6,6 +6,7 @@ import net.sergeych.bipack.BipackEncoder
 import net.sergeych.bipack.decodeFromBipack
 import net.sergeych.crypto2.Seal.Companion.create
 import net.sergeych.utools.now
+import kotlin.time.Duration.Companion.seconds
 
 /**
  * Extended public-key signature.
@@ -67,7 +68,7 @@ class Seal(
      */
     fun verify(message: UByteArray) {
         val n = now()
-        if (createdAt > n) throw IllegalSignatureException("signature's timestamp in the future")
+        if (createdAt - 45.seconds > n) throw IllegalSignatureException("signature's timestamp in the future: $createdAt / $n")
         expiresAt?.let {
             if (n >= it) throw ExpiredSignatureException("signature expired at $it")
         }