Function to save betas as a .nc file. This is utilized in gen.subdaily.models() when linear regression models are created
See also
Other tdm - Temporally Downscale Meteorology:
gen.subdaily.models(),
lm_ensemble_sims(),
model.train(),
nc.merge(),
predict_subdaily_met(),
save.model(),
subdaily_pred(),
temporal.downscale.functions()