Bump rocksdb to 0.19

[thibault-martinez]

Change checklist

• [ ] I have followed the contribution guidelines for this project
• [ ] I have performed a self-review of my own code
• [ ] I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation
• [ ] I have added tests that prove my fix is effective or that my feature works
• [ ] I have checked that new and existing unit tests pass locally with my changes
• [ ] I have updated the CHANGELOG.md, if my changes are significant enough