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

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https://hg.mozilla.org/integration/gaia-1_4/rev/a9285f475711
Author: Julien Wajsberg <felash@gmail.com>
Desc: Merge pull request #19556 from azasypkin/v1.4-bug-1013295-invalid-timestamp

 Bug 1013295 - [Messages] Migrated messages do not have a proper sentTimestamp. Hiding label with invalid timestamp. r=schung

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https://hg.mozilla.org/integration/gaia-1_4/rev/16a74a599218
Author: Aleh Zasypkin <azasypkin@mozilla.com>
Desc: Bug 1013295 - [Messages] Migrated messages do not have a proper sentTimestamp. Hiding label with invalid timestamp. r=schung
Bumping manifests a=b2g-bump