Use forked mkdocs-redirects (#2404)

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### What

Fix for #2222 (round 2)

[Related
commit](rerun-io/mkdocs-redirects@d367a08)
- it's just removing the `noindex` line from the redirect `index.html`
template. I have yet to confirm if this actually has the intended
effect, but it's the only `noindex` anywhere in the entire docs site,
and that's what google search console was complaining about. If this
works, I'll make a PR upstream with the fix.

### Checklist
* [ ] I have read and agree to [Contributor
Guide](https://github.com/rerun-io/rerun/blob/main/CONTRIBUTING.md) and
the [Code of
Conduct](https://github.com/rerun-io/rerun/blob/main/CODE_OF_CONDUCT.md)
* [ ] I've included a screenshot or gif (if applicable)

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PR Build Summary: https://build.rerun.io/pr/2404

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Docs preview: https://rerun.io/preview/6383747/docs
Examples preview: https://rerun.io/preview/6383747/examples
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---------

Co-authored-by: Emil Ernerfeldt <[email protected]>

rerun_py/requirements-doc.txt

@@ -3,7 +3,7 @@ mkdocs-gen-files
 mkdocs-literate-nav
 mkdocs-material
 mkdocs-material-extensions
-mkdocs-redirects
+git+https://github.com/rerun-io/mkdocs-redirects[email protected] # forked mkdocs-redirects with https://github.com/rerun-io/mkdocs-redirects/commit/d367a0847928438b66f73508e49852be1190409b
 mkdocstrings
 mkdocstrings-python
 mike