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

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https://hg.mozilla.org/integration/gaia-central/rev/376444b1a858
Author: Gareth Aye <gaye@mozilla.com>
Desc: Merge pull request #15079 from gaye/bug-952719

Bug 952719 - Reenable notification click message reader test

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https://hg.mozilla.org/integration/gaia-central/rev/7d7a5621b6b3
Author: Gareth Aye <gaye@mozilla.com>
Desc: Bug 952719 - Reenable notification click message reader test