### What this PR does / why we need it?
Fix:
```
DeprecationWarning: max_tokens is deprecated in favor of the max_completion_tokens field.
```
- vLLM version: v0.14.1
- vLLM main:
d68209402d
Signed-off-by: shen-shanshan <467638484@qq.com>
### What this PR does / why we need it?
Fix:
```
DeprecationWarning: max_tokens is deprecated in favor of the max_completion_tokens field.
```
- vLLM version: v0.14.1
- vLLM main:
d68209402d
Signed-off-by: shen-shanshan <467638484@qq.com>