### Check for existing issues

- [x] I have searched the existing issues and checked that my issue is not a duplicate.

### What happened?

Router.update_settings() raises an unhandled TypeError when None is passed for any integer setting (timeout, num_retries, retry_after, allowed_fails, cooldown_time).

Expected behavior: passing None should reset the setting to None without crashing.

I have a fix ready and will submit a PR immediately after filing this issue.

### Steps to Reproduce

1. Install litellm: pip install litellm

2. Run the following Python script:

from litellm import Router router = Router(model_list=[ {"model_name": "test", "litellm_params": {"model": "openai/gpt-4", "api_key": "sk-fake"}} ]) router.update_settings(timeout=None)

3. Observe TypeError is raised

### Relevant log output

```shell File "litellm/router.py", line 9523, in update_settings _casted_value = int(kwargs[var]) TypeError: int() argument must be a string, a bytes-like object or a real number, not 'NoneType' ```

### What part of LiteLLM is this about?

SDK (litellm Python package)

### What LiteLLM version are you on ?

v1.86.0

### Twitter / LinkedIn details

_No response_