[Chore] Replace all base64 usages with faster pybase64 package (#37290)

Signed-off-by: Isotr0py <mozf@mail2.sysu.edu.cn>

tests/models/multimodal/pooling/test_colqwen3.py

@@ -7,9 +7,9 @@ ColBERT-style late interaction scoring (MaxSim). It produces per-token
 embeddings for both text and image inputs.
 """
 
-import base64
 from io import BytesIO
 
+import pybase64 as base64
 import pytest
 import torch
 from PIL import Image