Bump mollie/mollie-api-php from 2.75.0 to 2.78.0

Bumps [mollie/mollie-api-php](https://github.com/mollie/mollie-api-php) from 2.75.0 to 2.78.0.
- [Release notes](https://github.com/mollie/mollie-api-php/releases)
- [Commits](mollie/mollie-api-php@v2.75.0...v2.78.0)

---
updated-dependencies:
- dependency-name: mollie/mollie-api-php
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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