### What this PR does / why we need it?
Bump default python version to 3.11, see #1980
### Does this PR introduce _any_ user-facing change?
no
### How was this patch tested?
pass CI
- vLLM version: v0.10.0
- vLLM main:
12a223ef9b
Signed-off-by: ChenTaoyu-SJTU <ctynb@qq.com>