cargo: bump axum from 0.6.1 to 0.6.4

Bumps [axum](https://github.com/tokio-rs/axum) from 0.6.1 to 0.6.4.
- [Release notes](https://github.com/tokio-rs/axum/releases)
- [Changelog](https://github.com/tokio-rs/axum/blob/main/CHANGELOG.md)
- [Commits](https://github.com/tokio-rs/axum/compare/axum-v0.6.1...axum-v0.6.4)

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

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

deltachat-jsonrpc/Cargo.toml

@@ -28,7 +28,7 @@ sanitize-filename = "0.4"
 walkdir = "2.3.2"
 
 # optional dependencies
-axum = { version = "0.6.1", optional = true, features = ["ws"] }
+axum = { version = "0.6.4", optional = true, features = ["ws"] }
 env_logger = { version = "0.10.0", optional = true }
 
 [dev-dependencies]