Bump uvloop from 0.17.0 to 0.19.0

Bumps [uvloop](https://github.com/MagicStack/uvloop) from 0.17.0 to 0.19.0.
- [Release notes](https://github.com/MagicStack/uvloop/releases)
- [Commits](MagicStack/uvloop@v0.17.0...v0.19.0)

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

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