Bump parallel_tests from 2.18.0 to 2.19.0
Bump parallel_tests from 2.18.0 to 2.19.0

Bumps [parallel_tests](https://github.com/grosser/parallel_tests) from 2.18.0 to 2.19.0.
- [Commits](https://github.com/grosser/parallel_tests/compare/v2.18.0...v2.19.0)
theodi/open-data-certificate,theodi/open-data-certificate,theodi/open-data-certificate,theodi/open-data-certificate