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

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https://hg.mozilla.org/integration/gaia-central/rev/2291c06ddc15
Author: Greg Weng <snowmantw@gmail.com>
Desc: Merge pull request #23309 from snowmantw/issue1055577

Bug 1055577 - [Lockscreen] Follow-up bug implement actionable Lockscreen...

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https://hg.mozilla.org/integration/gaia-central/rev/6255f9a92667
Author: Greg Weng <snowmantw@gmail.com>
Desc: Bug 1055577 - [Lockscreen] Follow-up bug implement actionable Lockscreen animation
Bumping manifests a=b2g-bump