[Bugfix] Replace unavailable video url in multimodal test (vllm-project#20854)

Signed-off-by: Isotr0py <2037008807@qq.com>
Signed-off-by: Jinzhen Lin <linjinzhen@hotmail.com>

Author: Isotr0py

tests/multimodal/test_utils.py

@@ -39,7 +39,7 @@
 
 TEST_VIDEO_URLS = [
     "https://www.bogotobogo.com/python/OpenCV_Python/images/mean_shift_tracking/slow_traffic_small.mp4",
-    "https://filesamples.com/samples/video/avi/sample_640x360.avi",
+    "https://github.com/opencv/opencv/raw/refs/tags/4.12.0/samples/data/vtest.avi",
 ]