fix tomllib error with python3.9

Author: YouNeedCryDear

.github/scripts/get_min_versions.py

@@ -1,9 +1,13 @@
 import sys
 
-import tomllib
 from packaging.version import parse as parse_version
 import re
 
+try:
+    import tomllib
+except ModuleNotFoundError:
+    import pip._vendor.tomli as tomllib
+
 MIN_VERSION_LIBS = ["langchain-core"]