Add missing default female hair texture for Ruth avatar.

This was not in library assets despite being referred to in assets/BodyPartsAssetSet/base_hair.dat
Texture ID is 7ca39b4c-bd19-4699-aff7-f93fd03d3e7b
Taken from https://github.com/openmetaversefoundation/simiangrid/blob/master/Grid/default_assets/Default%20Female%20Hair-7ca39b4c-bd19-4699-aff7-f93fd03d3e7b.j2c