Add JAX 0.8+ and 0.9+ compatibility

[mhliu0001]

This PR updates appletree to be compatible with JAX >= 0.8.0 while preserving backward compatibility with older supported JAX versions.

Summary

• Remove the JAX version upper bound (<0.8.0 → *) to support JAX 0.8.x and 0.9.x
• Replace all deprecated jnp.clip(x, a_min=..., a_max=...) keyword arguments with positional arguments, which work across all JAX versions
• Make the numpyro import in randgen.py conditional -- it is only needed on JAX < 0.4.21 (which lacks jax.random.binomial), so it no longer blocks import on JAX 0.9, where numpyro may not yet be compatible
• Use jax.default_backend() for platform detection with a fallback for older JAX versions

Testing

Tested for JAX 0.7.2, 0.8.3, 0.9.0.1.

[github-actions]

Pull Request Test Coverage Report for Build 21005071564

Details

• 14 of 17 (82.35%) changed or added relevant lines in 3 files are covered.
• 37 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.05%) to 84.065%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
appletree/config.py	0	1	0.0%
appletree/utils.py	4	6	66.67%

Files with Coverage Reduction	New Missed Lines	%
appletree/interpolation.py	15	72.05%
appletree/utils.py	22	62.19%

Totals
Change from base Build 18637300865:	-0.05%
Covered Lines:	2432
Relevant Lines:	2893

---

💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 22245185836

Details

• 20 of 24 (83.33%) changed or added relevant lines in 5 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-0.09%) to 84.191%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
appletree/config.py	0	1	0.0%
appletree/utils.py	4	5	80.0%
appletree/randgen.py	1	3	33.33%

Files with Coverage Reduction	New Missed Lines	%
appletree/utils.py	1	62.19%

Totals
Change from base Build 21965575783:	-0.09%
Covered Lines:	2471
Relevant Lines:	2935

---

💛 - Coveralls

[mhliu0001]

The code factor issues will be addressed in a separate PR.