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

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https://hg.mozilla.org/integration/gaia-central/rev/ff5977d5baae
Author: Sam Foster <sam@sam-i-am.com>
Desc: Merge pull request #23217 from sfoster/card-page-title-bug-1057396

Bug 1057396 - show page title in cards view. r=alive

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https://hg.mozilla.org/integration/gaia-central/rev/a0e1412d9914
Author: Sam Foster <sfoster@mozilla.com>
Desc: Bug 1057396 - display page title in cards view for browser windows
Bumping manifests a=b2g-bump