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

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https://hg.mozilla.org/integration/gaia-central/rev/aa767822ba3c
Author: Bob Silverberg <bob.silverberg@gmail.com>
Desc: Merge pull request #13704 from AndreiH/bug938550

Bug 938550 - Add MPL 2.0 license text to homescreen/regions/confirm_inst...

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https://hg.mozilla.org/integration/gaia-central/rev/b522390496d6
Author: Andrei Hutusoru <andreihutusoru@P5069.(none)>
Desc: Bug 938550 - Add MPL 2.0 license text to homescreen/regions/confirm_install.py