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

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https://hg.mozilla.org/integration/gaia-central/rev/61b250647043
Author: Yuren Ju <yurenju@gmail.com>
Desc: Merge pull request #15026 from yurenju/fix-gaia-build

Bug 956637 - gaia-build extension doesn't work after bug 922463 landed r=@timdream

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https://hg.mozilla.org/integration/gaia-central/rev/33dc5e569dcc
Author: Yuren Ju <yurenju@gmail.com>
Desc: Bug 956637 - gaia-build extension doesn't work after bug 922463 landed