audiowaveform: 1.4.2 -> 1.5.1, fix gtest subproject
Will be needed to fix build with gtest v1.11.0
(currently in staging-next #131928).
See https://github.com/bbc/audiowaveform/commit/7243739cb138e3952884786ba42694dd9ddc2c09
authored by Ryan Burns and committed by Raphael Megzari 000973d1 4dcf09ad