Build(deps): Bump symfony/slack-notifier from 5.3.4 to 5.4.0 (#1806)

Bumps [symfony/slack-notifier](https://github.com/symfony/slack-notifier) from 5.3.4 to 5.4.0.
- [Release notes](https://github.com/symfony/slack-notifier/releases)
- [Changelog](https://github.com/symfony/slack-notifier/blob/5.4/CHANGELOG.md)
- [Commits](symfony/slack-notifier@v5.3.4...v5.4.0)

---
updated-dependencies:
- dependency-name: symfony/slack-notifier
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

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