fix: Replace path.join with urljoin. (#2631)

api/core/model_runtime/model_providers/localai/llm/llm.py

 from collections.abc import Generator
-from os.path import join
 from typing import cast
+from urllib.parse import urljoin
 
 from httpx import Timeout
 from openai import (
         :param credentials: credentials dict
         :return: client kwargs
         """
+        if not credentials['server_url'].endswith('/'):
+            credentials['server_url'] += '/'
+            
         client_kwargs = {
             "timeout": Timeout(315.0, read=300.0, write=10.0, connect=5.0),
             "api_key": "1",
-            "base_url": join(credentials['server_url'], 'v1'),
+            "base_url": urljoin(credentials['server_url'], 'v1'),
         }
 
         return client_kwargs