schemars 0.9.0 [has been released](https://github.com/GREsau/schemars/releases/tag/v0.9.0) which is a precursor to 1.0.0. **serde_with** currently only has support for 0.8.0. When 0.9.0 is supported, minimal changes can be expected once 1.0.0 is released.