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

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https://hg.mozilla.org/integration/gaia-central/rev/5727c0abbf21
Author: Jose M. Cantera <jmcanterafonseca@gmail.com>
Desc: Merge pull request #12772 from gitmai/bug-914999-missing-mobile-number-on-export

Bug 914999 - Mobile phone is not well-formed on vcard export

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https://hg.mozilla.org/integration/gaia-central/rev/9dca9fb0099c
Author: mai <mri@tid.es>
Desc: Bug 914999 - Mobile phone is not well-formed on vcard export