Some pin_run_as_build pins are stricter than run_exports

[isuruf]

If the pin_run_as_build needs to be relaxed, we need to,

1. Hotfix the packages. eg: Fix expat pin to match run_exports conda-forge-repodata-patches-feedstock#132
2. Remove the pin_run_as_build or relax it.

There might be quite a few. I looked at the first one which is arpack and it needs to be fixed.

cc @ocefpaf, @beckermr

[beckermr]

Thanks for making this issue! We should I think prefer to remove pin_run_as_build as opposed to relaxing it so that we can centralize all ABI constraints around the run_exports themselves. Does this sound right?

If yes, then we may need to add run exports for older builds of pinned packages IIUIC.

[isuruf]

We should I think prefer to remove pin_run_as_build as opposed to relaxing it so that we can centralize all ABI constraints around the run_exports themselves. Does this sound right?

I think that's a related, but different issue.