feat: update installation to pyproject.toml & env.yml & update pre-commit

[MilagrosMarin]

This pull request modernizes the project's packaging and environment management by migrating from the legacy setup.py-based build system to a PEP 517/518-compliant pyproject.toml configuration. It also introduces a new Conda environment file for reproducible development environments and updates the pre-commit configuration to better control large file additions. This PR also fixes JAX compatibility issues, and all critical imports now work: jax, chex, optax, keypoint_moseq, dynamax.

Packaging and Build System Modernization:

• Added a pyproject.toml file to define project metadata, dependencies, and build configuration using the setuptools backend, replacing the previous setup.py approach. This aligns the project with current Python packaging standards.
• Removed the legacy setup.py file, fully transitioning packaging and dependency management to pyproject.toml.
• Fixed JAX compatibility issues.

Environment and Dependency Management:

• Added an env.yml file to specify a Conda environment for the project, ensuring consistent development and testing environments.

Pre-commit Configuration:

• Updated .pre-commit-config.yaml to set a maximum allowed file size (--maxkb=1000) for the check-added-large-files hook, preventing accidental commits of very large files.

Note: The keypoint-moseq version is currently 0.4.8 in this PR. It will be updated to the latest release in a future PR.