chore(deps-dev): bump datamodel-code-generator in /sdk/python

Bumps [datamodel-code-generator](https://github.com/koxudaxi/datamodel-code-generator) from 0.31.2 to 0.64.0.
- [Release notes](https://github.com/koxudaxi/datamodel-code-generator/releases)
- [Changelog](https://github.com/koxudaxi/datamodel-code-generator/blob/main/CHANGELOG.md)
- [Commits](koxudaxi/datamodel-code-generator@0.31.2...0.64.0)

---
updated-dependencies:
- dependency-name: datamodel-code-generator
  dependency-version: 0.64.0
  dependency-type: direct:development
...

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

Author: dependabot[bot]

sdk/python/pyproject.toml

@@ -28,7 +28,7 @@ Documentation = "https://github.com/openai/codex/tree/main/sdk/python/docs"
 format = ["ruff>=0.15.8"]
 test = [
   "pytest>=8.0",
-  "datamodel-code-generator==0.31.2",
+  "datamodel-code-generator==0.64.0",
   { include-group = "format" },
 ]
 dev = [