Bump trio from 0.19.0 to 0.21.0 (#1718)
Bump trio from 0.19.0 to 0.21.0 (#1718)

Bumps [trio](https://github.com/python-trio/trio) from 0.19.0 to 0.21.0.
- [Release notes](https://github.com/python-trio/trio/releases)
- [Commits](https://github.com/python-trio/trio/compare/v0.19.0...v0.21.0)

---
updated-dependencies:
- dependency-name: trio
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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Co-authored-by: dependabot[bot] <1c358da00a777d4e9898c1280ab801e2df165188@users.noreply.github.com>
Co-authored-by: Marcelo Trylesinski <5c86bce04fb7a3515a6d5a7f8f4be0d0fd9bf2f8@gmail.com>
encode/starlette,encode/starlette