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

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https://hg.mozilla.org/integration/gaia-central/rev/6ae26bd48965
Author: Luke Chang <lchang@mozilla.com>
Desc: Merge pull request #12929 from luke-chang/923653_support_contacts_layout

Bug 923653 - Layout of support contacts in settings isn't displayed properly, r=arthurcc

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https://hg.mozilla.org/integration/gaia-central/rev/a4f9970f8f57
Author: Luke Chang <lchang@mozilla.com>
Desc: Bug 923653 - Layout of support contacts in settings is not displayed properly