Update models.py to create models directory when its not present

It will create a models directory in current folder if it can't find the directory due to previous way where it tries to return models directory where its not present which in turns returns None causing os.path to fail
Fix #2030

g4f/locals/models.py

@@ -37,8 +37,10 @@ def get_model_dir() -> str:
     local_dir = os.path.dirname(os.path.abspath(__file__))
     project_dir = os.path.dirname(os.path.dirname(local_dir))
     model_dir = os.path.join(project_dir, "models")
-    if os.path.exists(model_dir):
-        return model_dir
+    if not os.path.exists(model_dir):
+        os.mkdir(model_dir)
+    return model_dir
+
 
 def get_models() -> dict[str, dict]:
     model_dir = get_model_dir()
@@ -48,4 +50,4 @@ def get_models() -> dict[str, dict]:
     else:
         models = load_models()
         save_models(file_path, models)
-        return models
+        return models