Bump php-http/discovery from 1.19.4 to 1.20.0

Bumps [php-http/discovery](https://github.com/php-http/discovery) from 1.19.4 to 1.20.0.
- [Release notes](https://github.com/php-http/discovery/releases)
- [Changelog](https://github.com/php-http/discovery/blob/1.x/CHANGELOG.md)
- [Commits](php-http/discovery@1.19.4...1.20.0)

---
updated-dependencies:
- dependency-name: php-http/discovery
  dependency-type: indirect
  update-type: version-update:semver-minor
...

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