Bump symfony/var-dumper from 5.4.39 to 5.4.40 in /modules/btcpay

Bumps [symfony/var-dumper](https://github.com/symfony/var-dumper) from 5.4.39 to 5.4.40.
- [Release notes](https://github.com/symfony/var-dumper/releases)
- [Changelog](https://github.com/symfony/var-dumper/blob/7.1/CHANGELOG.md)
- [Commits](symfony/var-dumper@v5.4.39...v5.4.40)

---
updated-dependencies:
- dependency-name: symfony/var-dumper
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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