ci: Pin Python version to at least 3.10 for LiteLLM (#5202)

Pin the minimum Python version for LiteLLM tests to 3.10. The library uses the vertical bar type union syntax, which causes a `TypeError` on import with Python 3.9.

Author: alexander-alderman-webb

scripts/populate_tox/config.py

@@ -231,6 +231,7 @@
     },
     "litellm": {
         "package": "litellm",
+        "python": ">3.9",  # https://github.com/BerriAI/litellm/issues/17701
     },
     "litestar": {
         "package": "litestar",