build(deps): bump ocpp from 2.0.0rc3 to 2.0.0rc4 in /tests/ocpp-server (#1266)

build(deps): bump ocpp from 2.0.0rc3 to 2.0.0rc4 in /tests/ocpp-server (#1266)

Bumps [ocpp](https://github.com/mobilityhouse/ocpp) from 2.0.0rc3 to 2.0.0rc4.
- [Release notes](https://github.com/mobilityhouse/ocpp/releases)
- [Changelog](https://github.com/mobilityhouse/ocpp/blob/master/CHANGELOG.md)
- [Commits](https://github.com/mobilityhouse/ocpp/compare/2.0.0-rc.3...2.0.0-rc.4)

---
updated-dependencies:
- dependency-name: ocpp
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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