chore(cargo): bump schemars from 0.8.19 to 0.8.21

Bumps [schemars](https://github.com/GREsau/schemars) from 0.8.19 to 0.8.21.
- [Release notes](https://github.com/GREsau/schemars/releases)
- [Changelog](https://github.com/GREsau/schemars/blob/master/CHANGELOG.md)
- [Commits](https://github.com/GREsau/schemars/compare/v0.8.19...v0.8.21)

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

Signed-off-by: dependabot[bot] <support@github.com>

deltachat-jsonrpc/Cargo.toml

@@ -17,7 +17,7 @@ anyhow = "1"
 deltachat = { path = ".." }
 deltachat-contact-tools = { path = "../deltachat-contact-tools" }
 num-traits = "0.2"
-schemars = "0.8.19"
+schemars = "0.8.21"
 serde = { version = "1.0", features = ["derive"] }
 tempfile = "3.10.1"
 log = "0.4"