python-for-hydrology

ci/requirements: resolve MODFLOW/Flopy COORDINATE_CHECK_METHOD conflict by pinning Flopy=3.9 for now. Flopy 3.10 wouldn't accept coordinate_check_method as an arg to the PRP package; for some reason installing MODFLOW from the modflow6 repo didn't result in version 6.7 for the PRT run in notebook 10a, even though the reported MODFLOW version in the path was 6.7.

ci(test.yaml):

fix(part1_flopy/10b_modpath_particle_tracking-demo.ipynb): restore outputs

feat(10a_prt_particle_tracking-demo.ipynb): add iflowface

fix(notebooks/part1_flopy/10a_prt_particle_tracking-demo.ipynb):