Run mkdocs gh-deploy before mike deploy on the Github workflow

[Shunpoco]

Expected Behavior

By #70 , 404.html was updated. So it was supposed that we could see the error page properly.

Actual Behavior

The error page is still broken.

Steps to Reproduce the Problem

Please see a wrong URL like https://kserve.github.io/website/0.7/admin/.

Additional Info

Cause

• On the Github workflow, we use mike deploy command to deploy our docs to Github-pages. Although mike updates versioned contents (/0.7/ and /latest/), it does not update contents on the root such like 404.html.
• If we access a wrong URL, Github-pages uses 404.html on the root as an error page. So currently we still see a broken error page if we access a wrong path.
• In addition, users can access not-version-controlled documents. If users access https://kserve.github.io/website/admin/serverless/, Github-pages return a content on the root. Because index.html redirects https://kserve.github.io/website/ to a specific version (in this case, https://kserve.github.io/website/0.7), but other paths are not redirected to a specific version. It might cause confusion.

Proposal

Run mkdocs gh-deploy command before we run mike deploy on Github workflow. So we can sync contents on the root with the latest contents.

Thanks!