fix: type mis-match between Context and model list

[congchan]

trafficstars

Why are these changes needed?

Current version of gradio_web_server cannot be served.

Related issue number (if applicable)

Checks

• [x] I've run format.sh to lint the changes in this PR.
• [x] I've included any doc changes needed.
• [x] I've made sure the relevant tests are passing (if applicable).