Fix links to Python examples

[abey79]

What

☝🏻

broken by #5966

Checklist

• I have read and agree to Contributor Guide and the Code of Conduct
• I've included a screenshot or gif (if applicable)
• I have tested the web demo (if applicable):
  • Using examples from latest main build: rerun.io/viewer
  • Using full set of examples from nightly build: rerun.io/viewer
• The PR title and labels are set such as to maximize their usefulness for the next release's CHANGELOG
• If applicable, add a new check to the release checklist!

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[github-actions]

Deployed docs

Commit	Link
8bc15ca	https://landing-6vn5e5cbz-rerun.vercel.app/docs

[teh-cmc]

Looking at the remaining ones.

[emilk]

I ran rg "examples/.*main.py" and:

This script should be fixed:

scripts/run_all.py
124:        for main_path in glob("examples/python/**/main.py"):

These links will break on next release, but it's unclear how we should fix that

• Versioned GitHub repository links from our docs #6077

examples/cpp/external_data_loader/README.md
3:python: https://github.com/rerun-io/rerun/tree/latest/examples/python/external_data_loader/main.py

examples/rust/external_data_loader/README.md
3:python: https://github.com/rerun-io/rerun/tree/latest/examples/python/external_data_loader/main.py

examples/python/external_data_loader/README.md
3:python: https://github.com/rerun-io/rerun/tree/latest/examples/python/external_data_loader/main.py

docs/content/reference/sdk-operating-modes.md
93:Check out our [dedicated example](https://github.com/rerun-io/rerun/tree/latest/examples/python/stdio/main.py).

docs/content/getting-started/data-in/python.md
16:At any time, you can checkout the complete code listing for this tutorial [here](https://github.com/rerun-io/rerun/tree/latest/examples/python/dna/main.py) to better keep track of the overall picture.

[abey79]

run_all.py is fully broken, not just paths:

• Replace run_all.py and nox with better alternatives #6057