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

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https://hg.mozilla.org/integration/gaia-central/rev/4455b1cc43cb
Author: Staś Małolepszy <stas@mozilla.com>
Desc: Merge pull request #18644 from stasm/1000874-findmydevice-once

Bug 1000874 - Clean up bootstrap mozL10n API use in FindMyDevice. r=dougt

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https://hg.mozilla.org/integration/gaia-central/rev/25c3a20ebd5c
Author: Staś Małolepszy <stas@mozilla.com>
Desc: Bug 1000874 - Clean up bootstrap mozL10n API use in FindMyDevice. r=dougt
Bumping manifests a=b2g-bump