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

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https://hg.mozilla.org/integration/gaia-central/rev/483c00ba2b0e
Author: Cristian Rodriguez <crdlc@tid.es>
Desc: Merge pull request #16509 from crdlc/bug-970225

Bug 970225 - [Download Manager] Confirmation screen is displayed once fo...

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https://hg.mozilla.org/integration/gaia-central/rev/7c6e2620aa11
Author: crdlc <crdlc@tid.es>
Desc: Bug 970225 - [Download Manager] Confirmation screen is displayed once for each selected file
Bumping manifests a=b2g-bump