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

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https://hg.mozilla.org/integration/gaia-central/rev/feecd912cae7
Author: Aleh Zasypkin <aleh.zasypkin@gmail.com>
Desc: Merge pull request #23685 from azasypkin/bug-1048717-call-button-refresh

Bug 1048717 - [Messages][Refresh] Display call button at the header of single recipient thread. r=schung

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https://hg.mozilla.org/integration/gaia-central/rev/7a179629af1b
Author: Aleh Zasypkin <azasypkin@mozilla.com>
Desc: Bug 1048717 - [Messages][Refresh] Display call button at the header of single recipient thread. r=schung
Bumping manifests a=b2g-bump