[pip] Dependabot: Bump ddtrace from 2.21.2 to 2.21.3

Bumps [ddtrace](https://github.com/DataDog/dd-trace-py) from 2.21.2 to 2.21.3.
- [Release notes](https://github.com/DataDog/dd-trace-py/releases)
- [Changelog](https://github.com/DataDog/dd-trace-py/blob/main/CHANGELOG.md)
- [Commits](DataDog/dd-trace-py@v2.21.2...v2.21.3)

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

Signed-off-by: dependabot[bot] <[email protected]>