build(deps): Bump uvloop from 0.20.0 to 0.21.0 (#555)

Bumps [uvloop](https://github.com/MagicStack/uvloop) from 0.20.0 to 0.21.0.
- [Release notes](https://github.com/MagicStack/uvloop/releases)
- [Commits](MagicStack/uvloop@v0.20.0...v0.21.0)

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

requirements.txt

@@ -37,5 +37,5 @@ asyncstdlib==3.12.5
 cachetools==5.5.0
 CJKwrap==2.2
 typing-extensions==4.12.2
-uvloop==0.20.0; sys_platform!='win32' and sys_platform!='cygwin' and sys_platform!='cli'
+uvloop==0.21.0; sys_platform!='win32' and sys_platform!='cygwin' and sys_platform!='cli'
 isal==1.7.1; platform_machine=='x86_64' or platform_machine=='AMD64' or platform_machine=='aarch64'