Machine-Learning-Dynamical-Systems/kooplearn: kooplearn 2.0.3 — JOSS review revisions

This release incorporates the revisions made during the JOSS review of kooplearn. Highlights: Fixed pytest collection when optional torch / jax dependencies are not installed. Stabilized reviewer-reported test failures. Cleaned the JOSS paper bibliography, title casing, and minor typos. Expanded installation, testing, and contributor documentation. Added CODE_OF_CONDUCT.md, issue templates, and a pull request template. Added CI coverage reporting with Codecov. Cleaned notebook metadata so example notebooks render correctly on GitHub. Declared missing runtime and development dependencies. This is the release associated with the JOSS-reviewed version of kooplearn. What's Changed Prepare JOSS submission by @g-turri in https://github.com/Machine-Learning-Dynamical-Systems/kooplearn/pull/23 Address JOSS review revisions by @g-turri in https://github.com/Machine-Learning-Dynamical-Systems/kooplearn/pull/32 Full Changelog: https://github.com/Machine-Learning-Dynamical-Systems/kooplearn/compare/v2.0.2...v2.0.3