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

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https://hg.mozilla.org/integration/gaia-central/rev/aa7afb132e75
Author: Francisco Jordano <arcturus@ardeenelinfierno.com>
Desc: Merge pull request #12440 from jmcanterafonseca/bug_export_checks

Bug 920476 [Contacts] Not possible to select a contact to be exported

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https://hg.mozilla.org/integration/gaia-central/rev/555cbb489dd0
Author: Jose M. Cantera <jmcanterafonseca@gmail.com>
Desc: Bug 920476 [Contacts] Not possible to select a contact to be exported