Bumping gaia.json for 1 gaia-1_2 revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-1_2/rev/4eb29d5a57de
Author: Fernando Campo <fernando.campo@o2.com>
Desc: Merge pull request #13955 from fcampo/exported-label-translate-929552

Bug 936889 - Followup for bug 929552 - Sync string for exported contacts (r=pike)(cherry picked from commit 10e5cd63155a41927b9fa3b5a2bd0726ed85f1ab)

Conflicts:
	apps/communications/contacts/locales/contacts.en-US.properties