fix: Update LLMEndpoint to include max_tokens parameter (#3201)

# Description

Please include a summary of the changes and the related issue. Please
also include relevant motivation and context.

## Checklist before requesting a review

Please delete options that are not relevant.

- [ ] My code follows the style guidelines of this project
- [ ] I have performed a self-review of my code
- [ ] I have commented hard-to-understand areas
- [ ] I have ideally added tests that prove my fix is effective or that
my feature works
- [ ] New and existing unit tests pass locally with my changes
- [ ] Any dependent changes have been merged

## Screenshots (if appropriate):

backend/core/quivr_core/llm/llm_endpoint.py

@@ -42,6 +42,7 @@ def from_config(cls, config: LLMEndpointConfig = LLMEndpointConfig()):
                     if config.llm_api_key
                     else None,
                     azure_endpoint=azure_endpoint,
+                    max_tokens=config.max_tokens
                 )
             elif config.model.startswith("claude"):
                 _llm = ChatAnthropic(
@@ -50,6 +51,7 @@ def from_config(cls, config: LLMEndpointConfig = LLMEndpointConfig()):
                     if config.llm_api_key
                     else None,
                     base_url=config.llm_base_url,
+                    max_tokens=config.max_tokens
                 )
             else:
                 _llm = ChatOpenAI(
@@ -58,6 +60,7 @@ def from_config(cls, config: LLMEndpointConfig = LLMEndpointConfig()):
                     if config.llm_api_key
                     else None,
                     base_url=config.llm_base_url,
+                    max_tokens=config.max_tokens
                 )
             return cls(llm=_llm, llm_config=config)