PEP 819: Update Discussion-To and Post-History

[emmatyping-nv]

• Change is either:
  • To a Draft PEP
  • To an Accepted or Final PEP, with Steering Council approval
  • To fix an editorial issue (markup, typo, link, header, etc)
• PR title prefixed with PEP number (e.g. PEP 123: Summary of changes)

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📚 Documentation preview 📚: https://pep-previews--4772.org.readthedocs.build/

[emmatyping]

Oh, forgot to switch accounts, but this is by me :)

[hugovk]

Thanks both :)