Bump mockito version to 3.4.0
Bump mockito version to 3.4.0

PiperOrigin-RevId: 377064882

google/ExoPlayer,amzn/exoplayer-amazon-port,ened/ExoPlayer,amzn/exoplayer-amazon-port,google/ExoPlayer,ened/ExoPlayer,ened/ExoPlayer,amzn/exoplayer-amazon-port,google/ExoPlayer,androidx/media,androidx/media,androidx/media