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

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https://hg.mozilla.org/integration/gaia-central/rev/f8c959689b7c
Author: Aleh Zasypkin <aleh.zasypkin@gmail.com>
Desc: Merge pull request #22180 from azasypkin/bug-1026694-attach-button

Bug 1026694 - Access to attach button. r=schung

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https://hg.mozilla.org/integration/gaia-central/rev/deed20d36973
Author: Aleh Zasypkin <azasypkin@mozilla.com>
Desc: Bug 1026694 - Access to attach button. r=schung
Bumping manifests a=b2g-bump