Fix incorrect unk_id assignment

tokenization_kimia.py

@@ -127,7 +127,7 @@ class TikTokenTokenizer(PreTrainedTokenizer):
         self.pad_id: int = self.special_tokens[self.pad_token]
 
         self.unk_token: str = special_tokens[-2]
-        self.unk_id: int = self.special_tokens[self.pad_token]
+        self.unk_id: int = self.special_tokens[self.unk_token]
 
         self.stop_tokens = {
             self.special_tokens["[EOS]"],