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

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https://hg.mozilla.org/integration/gaia-central/rev/4523a8f13fa6
Author: Alive.Kuo <alegnadise@gmail.com>
Desc: Merge pull request #15595 from alivedise/bugzilla/962499/remove-manifestURLs

Bug 962499 - Remove manifestURLs in connections.*.rules, r=vivien

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https://hg.mozilla.org/integration/gaia-central/rev/214fda9befc2
Author: Alive Kuo <alegnadise@gmail.com>
Desc: Bug 962499 - Remove manifestURLs in connections.*.rules
Bumping manifests a=b2g-bump