Bump gradio from 4.11.0 to 4.19.2 in /examples/web_demo (#241)

Author: dependabot[bot]

examples/web_demo/requirements.txt

@@ -1,5 +1,5 @@
 -f https://download.pytorch.org/whl/torch_stable.html
-gradio==4.11.0
+gradio==4.19.2
 gradio_client==0.7.3
 sentencepiece==0.1.99
 torch==2.0.1+cpu