add jpeg codec and testcases - #81

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/setup-java@v4, actions/upload-artifact@v4, astral-sh/setup-uv@v6. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

No file matched to [/home/runner/work/zarr-java/zarr-java/**/*requirements*.txt,/home/runner/work/zarr-java/zarr-java/**/*requirements*.in,/home/runner/work/zarr-java/zarr-java/**/*constraints*.txt,/home/runner/work/zarr-java/zarr-java/**/*constraints*.in,/home/runner/work/zarr-java/zarr-java/**/pyproject.toml,/home/runner/work/zarr-java/zarr-java/**/uv.lock,/home/runner/work/zarr-java/zarr-java/**/*.py.lock]. The cache will never get invalidated. Make sure you have checked out the target repository and configured the cache-dependency-glob input correctly.

setup-java v4 is deprecated and will no longer receive updates. Please migrate to actions/setup-java@v5.