Bump uvloop from 0.15.2 to 0.15.3

Bumps [uvloop](https://github.com/MagicStack/uvloop) from 0.15.2 to 0.15.3.
- [Release notes](https://github.com/MagicStack/uvloop/releases)
- [Commits](https://github.com/MagicStack/uvloop/compare/v0.15.2...v0.15.3

)

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

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