add run-export to libpython

[h-vetinari]

For users of libpython like lldb, we should IMO indicate the dependence with a host: dependence as usual, and then inherit the run-export, also as usual. For py<315 this is less relevant (except for the link check), but for 3.15+, where libpython3.{so,dylib} is not part of the python package anymore, this would make sense IMO.

If/once merged, it would also be reasonable to backport this to past python versions IMO, if only for consistency (and again the link check).

[conda-forge-admin]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe/meta.yaml) and found it was in an excellent condition.

I do have some suggestions for making it better though...

For recipe/meta.yaml:

• ℹ️ The recipe is not parsable by parser conda-souschef (grayskull). This parser is not currently used by conda-forge, but may be in the future. We are collecting information to see which recipes are compatible with grayskull.
• ℹ️ The recipe is not parsable by parser conda-recipe-manager. The recipe can only be automatically migrated to the new v1 format if it is parseable by conda-recipe-manager.

_{This message was generated by GitHub Actions workflow run https://github.com/conda-forge/conda-forge-webservices/actions/runs/34112621565. Examine the logs at this URL for more detail.}