Also fix import here

Author: bsquizz

src/tangerine/vector.py

@@ -4,7 +4,7 @@
 import math
 import re
 
-from langchain.text_splitter import MarkdownHeaderTextSplitter, RecursiveCharacterTextSplitter
+from langchain_classic.text_splitter import MarkdownHeaderTextSplitter, RecursiveCharacterTextSplitter
 from langchain_core.documents import Document
 from langchain_postgres.vectorstores import PGVector
 from sqlalchemy import text