Include more recent UM output test data files

[jamesp]

The FF files included in this repository are from old versions of the UM which may not be representative of user datafiles.

This repository should be updated to include data from more recent versions of the UM that more accurately represent real-world usage.

Further detail

The current version of the UM is 12.0. Running a quick assessment of the FF files in this repo shows they are mostly from UM 8, the most recent from UM 10.

find test_data/FF -type f  -exec mule-pumf {}  --headers-only 2> /dev/null \; | grep model_version
  (12) model_version                     :    709
  (12) model_version                    :      606
  (12) model_version                     :    805
  (12) model_version                    :    902
  (12) model_version                    :   1003
  (12) model_version                    :   805
  (12) model_version                     :         802
  (12) model_version                     :         802
  (12) model_version                     :         805