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

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https://hg.mozilla.org/integration/gaia-central/rev/c54d0889b5be
Author: Timothy Guan-tin Chien <timdream@gmail.com>
Desc: Merge pull request #13769 from timdream/lockscreen-unlock-transition

Bug 937630 - All you need is ... smooth unlock transition, r=vingtetun

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https://hg.mozilla.org/integration/gaia-central/rev/953a17ca4d5b
Author: Timothy Guan-tin Chien <timdream@gmail.com>
Desc: Bug 937630 - All you need is ... smooth unlock transition