Update attohttpc requirement from 0.27 to 0.28

Updates the requirements on [attohttpc](https://github.com/sbstp/attohttpc) to permit the latest version.
- [Release notes](https://github.com/sbstp/attohttpc/releases)
- [Commits](sbstp/attohttpc@v0.27.0...v0.28.0)

---
updated-dependencies:
- dependency-name: attohttpc
  dependency-type: direct:production
...

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

codegen/Cargo.toml

@@ -5,7 +5,7 @@ authors = ["Steven Fackler <sfackler@gmail.com>"]
 edition = "2021"
 
 [dependencies]
-attohttpc = "0.27"
+attohttpc = "0.28"
 marksman_escape = "0.1"
 regex = "1.0"
 thiserror = "1.0"