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

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https://hg.mozilla.org/integration/gaia-central/rev/5902fbe1799a
Author: Francisco Jordano <arcturus@ardeenelinfierno.com>
Desc: Merge pull request #15169 from arcturus/bug-935626

Bug-951287 Multiline quoted encoding elemnets in vcard files

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https://hg.mozilla.org/integration/gaia-central/rev/a98ff740c2b1
Author: Francisco Jordano <arcturus@ardeenelinfierno.com>
Desc: Bug-951287 Multiline quoted encoding elemnets in vcard files
Bumping manifests a=b2g-bump