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

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https://hg.mozilla.org/integration/gaia-central/rev/376673782b79
Author: Florin Strugariu <bebef_1987@yahoo.com>
Desc: Merge pull request #15765 from zacc/bug_964722

Bug 964722 - Refactor and reenable test_dialer_add_contact.py for desktop and device r=bebe

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https://hg.mozilla.org/integration/gaia-central/rev/53874deb3b31
Author: Zac Campbell <zcampbell@mozilla.com>
Desc: Bug 964722 - Refactor and reenable test_dialer_add_contact.py for desktop and device r=bebe
Bumping manifests a=b2g-bump