Bump sentry/sentry from 3.19.1 to 3.21.0

Bumps [sentry/sentry](https://github.com/getsentry/sentry-php) from 3.19.1 to 3.21.0.
- [Release notes](https://github.com/getsentry/sentry-php/releases)
- [Changelog](https://github.com/getsentry/sentry-php/blob/master/CHANGELOG.md)
- [Commits](getsentry/sentry-php@3.19.1...3.21.0)

---
updated-dependencies:
- dependency-name: sentry/sentry
  dependency-type: indirect
  update-type: version-update:semver-minor
...

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