Update jaxlib requirement from <=0.4.14 to <=0.4.20 in /tests

Updates the requirements on [jaxlib](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...jaxlib-v0.4.20)

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

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

tests/constraints.txt

@@ -22,5 +22,5 @@ pytest-dependency==0.5.1
 pytest-html==3.2.0
 pytest-timeout==2.1.0
 jax<=0.4.14
-jaxlib<=0.4.14
+jaxlib<=0.4.20
 torch<2.1.0,>=1.13