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

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https://hg.mozilla.org/integration/gaia-central/rev/c9c11ebb5342
Author: Jose M. Cantera <jmcanterafonseca@gmail.com>
Desc: Merge pull request #12631 from gitmai/bug-880775-birthday-timezone-error

Bug 880775 - Birthday timezone error

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https://hg.mozilla.org/integration/gaia-central/rev/bb80a61e4e57
Author: mai <mri@tid.es>
Desc: Bug 880775 - Birthday timezone error