### Bug description

I am attempting to install a quarto extension for section bibliographies into a Quarto Book project using PowerShell.
https://github.com/pandoc-ext/section-bibliographies#quarto

When I attempt to do so, I receive this error
![image](https://github.com/quarto-dev/quarto-cli/assets/25335087/83a52c51-1b97-48b1-a0de-01e56783df87)

My project has my company's `http_proxy` and `https_proxy` defined in the `.Rprofile`

It is not clear from `quarto help` how the user would verify quarto can see these proxy settings.

### Checklist

- [ ] Please include a minimal, fully reproducible example in a single .qmd file? Please provide the whole file rather than the snippet you believe is causing the issue.
- [ ] Please [format your issue](https://quarto.org/bug-reports.html#formatting-make-githubs-markdown-work-for-us) so it is easier for us to read the bug report.
- [ ] Please document the RStudio IDE version you're running (if applicable), by providing the value displayed in the "About RStudio" main menu dialog?
- [ ] Please document the operating system you're running. If on Linux, please provide the specific distribution.
- [ ] Please provide the output of `quarto check` so we know which version of quarto and its dependencies you're running.
dragonstyle
2023-05-12T12:54:53Z
matthewdwood82
enhancement
v1.4
open
Support proxy definition for fetch operation by using custom http client using proxy env var or flags to command line
https://github.com/quarto-dev/quarto-cli/issues/5515