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

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https://hg.mozilla.org/integration/gaia-central/rev/0a271036d832
Author: Zac <zcampbell@mozilla.com>
Desc: Merge pull request #18328 from viorelaioia/update_email_test

Bug 968744 - Update test_receive_active_sync_email to check for incoming notification

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https://hg.mozilla.org/integration/gaia-central/rev/5d12df3071fe
Author: Viorela Ioia <viorelaioia@gmail.com>
Desc: Bug 968744 - Update test_receive_active_sync_email to check for incoming notification
Bumping manifests a=b2g-bump