Add sentence_transformers to CI dependency (sgl-project#1958)

scripts/ci_install_dependency.sh

@@ -4,5 +4,5 @@ Install the dependency in CI.
 
 pip install --upgrade pip
 pip install -e "python[all]"
-pip install transformers==4.45.2
+pip install transformers==4.45.2 sentence_transformers
 pip install flashinfer -i https://flashinfer.ai/whl/cu121/torch2.4/ --force-reinstall