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

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https://hg.mozilla.org/integration/gaia-central/rev/db6b845afaad
Author: Marcus Cavanaugh <m@mcav.com>
Desc: Merge pull request #20988 from mcav/gelam-epoch

Bug 941991 - [Email] Sync falls into the epoch. r=jrburke

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https://hg.mozilla.org/integration/gaia-central/rev/d601d98ef45c
Author: Marcus Cavanaugh <m@mcav.com>
Desc: Bug 941991 - [Email] Sync falls into the epoch. r=jrburke
Bumping manifests a=b2g-bump