Unexpected BIPM warning when used with NG20 default (BIPM2023)

[rossjjennings]

Currently, running through the NANOGrav 20-year notebook with bipm in the configuration file set to BIPM2023 gives the following warning:

WARNING: Wrong bipm_version (BIPM2023); should be BIPM2021. [pint_pal.par_checker]

#63 was supposed to have taken care of this (via the pint_pal_project.yaml in the NG20 repository), but it doesn't seem to be working: par_checker is still using recommendations from PINT Pal's defaults.yaml instead of the NG20 ones.