R CMD check found WARNINGs

Process completed with exit code 1.

Node.js 16 actions are deprecated. Please update the following actions to use Node.js 20: actions/checkout@v3, actions/upload-artifact@v2. For more information see: https://github.blog/changelog/2023-09-22-github-actions-transitioning-from-node-16-to-node-20/.

The following actions uses node12 which is deprecated and will be forced to run on node16: actions/upload-artifact@v2. For more info: https://github.blog/changelog/2023-06-13-github-actions-all-actions-will-run-on-node16-instead-of-node12-by-default/

Undocumented code objects:

Non-portable flags in variable 'PKG_CXXFLAGS':

Undocumented code objects: