Update jax[cpu] requirement from <0.4.20 to <0.4.21

Updates the requirements on [jax[cpu]](https://github.com/google/jax) to permit the latest version.
- [Release notes](https://github.com/google/jax/releases)
- [Changelog](https://github.com/google/jax/blob/main/CHANGELOG.md)
- [Commits](jax-ml/jax@jaxlib-v0.1.32...jax-v0.4.20)

---
updated-dependencies:
- dependency-name: jax[cpu]
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <[email protected]>

setup.py

@@ -9,7 +9,7 @@
 # `pyproject.toml`, once optional dependencies defined there can reference one another
 extras_require = dict()
 extras_require["jax"] = [
-    "jax[cpu]<0.4.20; platform_system!='Windows'",
+    "jax[cpu]<0.4.21; platform_system!='Windows'",
 ]
 extras_require["zoo"] = [
     "tqdm>=4.0",