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

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https://hg.mozilla.org/integration/gaia-central/rev/7a1b79298722
Author: dwi2 <dwi2@dwi2.com>
Desc: Merge pull request #13685 from dwi2/bug881957

Bug 881957 - Implement toast and show toast after successfully change PIN

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https://hg.mozilla.org/integration/gaia-central/rev/7da37862265e
Author: tzhuang <tzhuang@mozilla.com>
Desc: Bug 881957 - Implement toast and show toast after successfully change PIN
Bumping manifests a=b2g-bump