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

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https://hg.mozilla.org/integration/gaia-central/rev/74d057346452
Author: Cristian Rodriguez <crdlc@tid.es>
Desc: Merge pull request #13949 from crdlc/bug-datastore-download

Bug 941694 - [Download Manager] New library to store the complete downlo...

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https://hg.mozilla.org/integration/gaia-central/rev/e92590626ec0
Author: crdlc <crdlc@tid.es>
Desc: Bug 941694 - [Download Manager] New library to store the complete downloads