Run-export should be vtk-base

[h-vetinari]

Given that that's the output where all the libraries are, the link check does not care bout a vtk-rundependence, but will warn:

Needed DSO lib/libvtkWrappingPythonCore3.9-9.2.1.dylib found in ['vtk-base']
.. but ['vtk-base'] not in reqs/run, (i.e. it is overlinking) (likely) or a missing
[...]
run-exports library package conda-forge::vtk-9.2.6-qt_py39h1234567_214 in requirements/run but it is not used (i.e. it is overdepending or perhaps statically linked? If that is what you want then add it to `build/ignore_run_exports`)