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

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https://hg.mozilla.org/integration/gaia-central/rev/63153dfd1199
Author: Ryan VanderMeulen <rvandermeulen@mozilla.com>
Desc: Merge pull request #15022 from Archaeopteryx/ftu-nitpicking-bug939576

Bug 935976 - [first run] tutorial: "ﬁ" in "notiﬁcations" is one character, should be two (= "notifications") and other nitpicking. r=fcampo

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https://hg.mozilla.org/integration/gaia-central/rev/31157f8a95db
Author: Sebastian Hengst <archaeopteryx@coole-files.de>
Desc: Bug 935976 - [first run] tutorial: "ﬁ" in "notiﬁcations" is one character, should be two (= "notifications") and other nitpicking