publish workflow failing with pipx error

[braingram]

https://github.com/spacetelescope/jwst/actions/runs/30093150136/job/89480790061

Run pipx run load_build_targets.py --targets "${INPUTS_TARGETS}"
This package needs a Python matching '==3.12' and none of the interpreters on
this system does. Install one of 3.12, name it with --python, or pass
--fetch-python=missing to let pipx download it.
Error: Process completed with exit code 1.

Perhaps related to #291

[neutrinoceros]

fixed in #410