Netlify preview is currently failing with the following error:

```
Collecting git+git://github.com/cilium/sphinx_rtd_theme.git@v0.7 (from -r requirements.txt (line 23))
  Cloning git://github.com/cilium/sphinx_rtd_theme.git (to revision v0.7) ...
  Running command git clone -q git://github.com/cilium/sphinx_rtd_theme.git ...
  fatal: remote error:
    The unauthenticated git protocol on port 9418 is no longer supported.
  Please see https://github.blog/2021-09-01-improving-git-protocol-security-github/ for more information.
```

Signed-off-by: Michi Mutsuzaki <michi@isovalent.com>