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

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https://hg.mozilla.org/integration/gaia-central/rev/7a57536f1a7a
Author: AndreiH <andrei.hutusoru@softvision.ro>
Desc: Merge pull request #19633 from viorelaioia/bug_1011469_v2.0

Bug 1011469 - Intermittent in cost control tests, tapping Next button ha...

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https://hg.mozilla.org/integration/gaia-central/rev/b71e9aac1fe8
Author: Viorela Ioia <viorelaioia@gmail.com>
Desc: Bug 1011469 - Intermittent in cost control tests, tapping Next button has no effect
Bumping manifests a=b2g-bump