Bumping gaia.json for 4 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/6b89c1234248
Author: Justin D'Arcangelo <justindarc@gmail.com>
Desc: Merge pull request #18054 from wilsonpage/991856

Bug 991856 - [Camera][Madai] Implement the new design for the focus ring

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https://hg.mozilla.org/integration/gaia-central/rev/55dd56bea3be
Author: Wilson Page <wilsonpage@me.com>
Desc: Bug 991856 - [Camera][Madai] Implement the new design for the focus ring

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https://hg.mozilla.org/integration/gaia-central/rev/7fde9553802b
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #18336 from guilherme-pg/bug996683

Bug 996683 - Poll for the lockscreen message to show up.

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https://hg.mozilla.org/integration/gaia-central/rev/abec817c4f80
Author: Guilherme Goncalves <guilherme.p.gonc@gmail.com>
Desc: Bug 996683 - Poll for the lockscreen message to show up.
Bumping manifests a=b2g-bump