v0.18.2 Add core::error::Error implementation to non_std build

What's Changed

• Implement core::error::Error for the error types by @xyzzyz in #127
• Increment version 0.18.2 by @JulianSchmid in #128

New Contributors

• @xyzzyz made their first contribution in #127

Full Changelog: v0.18.1...v0.18.2