Bump trio from 0.19.0 to 0.20.0 (#2197)

Bump trio from 0.19.0 to 0.20.0 (#2197)

Bumps [trio](https://github.com/python-trio/trio) from 0.19.0 to 0.20.0.
- [Release notes](https://github.com/python-trio/trio/releases)
- [Commits](https://github.com/python-trio/trio/compare/v0.19.0...v0.20.0)

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

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Co-authored-by: Tom Christie <tom@tomchristie.com>