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

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https://hg.mozilla.org/integration/gaia-1_3/rev/4246ad5fa5c5
Author: Zac <zcampbell@mozilla.com>
Desc: Merge pull request #18125 from viorelaioia/bug_992181

Bug 992181 - [1.3] Wait for ready event before Persona signin

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https://hg.mozilla.org/integration/gaia-1_3/rev/e0f2d8bca424
Author: Viorela Ioia <viorelaioia@gmail.com>
Desc: Bug 992181 - [1.3] Wait for ready event before Persona signin
Bumping manifests a=b2g-bump