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

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https://hg.mozilla.org/integration/gaia-central/rev/fca5b0c5b448
Author: Luke Chang <lchang@mozilla.com>
Desc: Merge pull request #13161 from luke-chang/919370_unit_test_for_pinyin

Bug 919370 - [Test][Keyboard] Unit test for Pinyin IME, r=rudylu

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https://hg.mozilla.org/integration/gaia-central/rev/51e3c069e2e2
Author: Luke Chang <lchang@mozilla.com>
Desc: Bug 919370 - [Test][Keyboard] Unit test for Pinyin IME