add aurora platform

lib/src/kdbx_entry.dart

@@ -57,6 +57,7 @@ bool kdbxKeyCommonAssertConsistency() {
 class KdbxKey {
   KdbxKey(this.key) : _canonicalKey = key.toLowerCase();
   const KdbxKey._(this.key, this._canonicalKey);
+  const KdbxKey.origin(this.key, this._canonicalKey);
 
   final String key;
   final String _canonicalKey;