feat: update deltachat-core to 0.38.0

deltachat-ios/Wrapper.swift

@@ -313,7 +313,7 @@ class MRMessage: MessageType {
   }
 
   var timestamp: Int64 {
-    return Int64(messagePointer.pointee.timestamp)
+    return Int64(dc_msg_get_timestamp(messagePointer))
   }
 
   var isInfo: Bool {

deltachat-ios/libraries/deltachat-core

@@ -1 +1 @@
-Subproject commit 26cc5d82a7b759af9e16cdd10eb2335ad3270db7
+Subproject commit 6dc4063c7734377f1a3ebc151e86d96a5aa027e0