Bumping gaia.json for 2 gaia revision(s) a=gaia-bump

========

https://hg.mozilla.org/integration/gaia-central/rev/5aaf8846e318
Author: Rudy Lu <me@rudy.lu>
Desc: Merge pull request #21447 from RudyLu/music/Bug1032757_reenable_player_test_commit

Bug 1032757 - Re-enable Music player tests - Playback tests.
r=jimporter.

========

https://hg.mozilla.org/integration/gaia-central/rev/37282e005d9b
Author: Rudy Lu <me@rudy.lu>
Desc: Bug 1032757 - Re-enable Music player tests - Playback tests.
 - get progress while the music app is in background
Bumping manifests a=b2g-bump