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

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https://hg.mozilla.org/integration/gaia-central/rev/c0acdfd2a62e
Author: Luke Chang <lchang@mozilla.com>
Desc: Merge pull request #18221 from luke-chang/991509_tamil_input_method

Bug 991509 - Adding Tamil input method for B2G, r=rudylu

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https://hg.mozilla.org/integration/gaia-central/rev/d317ec8200b1
Author: Luke Chang <lchang@mozilla.com>
Desc: Bug 991509 - Adding Tamil input method for B2G
Bumping manifests a=b2g-bump