Bumping gaia.json for 3 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/629c07ba7b49
Author: Eitan Isaacson <eitan@monotonous.org>
Desc: Bug 1091731 - Introduce gaia-select webcomponent.

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https://hg.mozilla.org/integration/gaia-central/rev/6c7072c7b42b
Author: Julien Wajsberg <felash@gmail.com>
Desc: Merge pull request #25513 from julienw/move-sticky-header-out-of-launch-path

Bug 1089145 - [Messages] Move the sticky header init out of the critical...

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https://hg.mozilla.org/integration/gaia-central/rev/db2d7b1eb853
Author: Julien Wajsberg <felash@gmail.com>
Desc: Bug 1089145 - [Messages] Move the sticky header init out of the critical path r=schung,kgrandon
Bumping manifests a=b2g-bump