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

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https://hg.mozilla.org/integration/gaia-central/rev/dfdbfe831e9f
Author: Rudy Lu <me@rudy.lu>
Desc: Merge pull request #19108 from RudyLu/pr16829_squash

Bug 953033 - Add Dzongkha Input Method for B2G.
r=rudylu

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https://hg.mozilla.org/integration/gaia-central/rev/0d6178e8cbe9
Author: Rabbi Hossain <rabbihossain@users.noreply.github.com>
Desc: Bug 953033 - Add Dzongkha Input Method for B2G.
Bumping manifests a=b2g-bump