Ignore NotImplementedError exceptions on pygame.mixer, which happen if the mixer module fails to initialise.
Ignore NotImplementedError exceptions on pygame.mixer, which happen if the
mixer module fails to initialise.

PiperOrigin-RevId: 285200975
Change-Id: I2fe5ac8553c7bc1398e0e923065fb0ad491b624a

deepmind/dm_memorytasks