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

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https://hg.mozilla.org/integration/gaia-central/rev/1a21ee5cb627
Author: James Burke <jrburke@gmail.com>
Desc: Merge pull request #15581 from jrburke/bug962257-email-link-blank

Bug 962257 - [B2G][Email][Browser] Link navigates to blank screen when s... r=asuth

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https://hg.mozilla.org/integration/gaia-central/rev/a06a32cf31f1
Author: jrburke <jrburke@gmail.com>
Desc: Bug 962257 - [B2G][Email][Browser] Link navigates to blank screen when sharing an email link in browser
Bumping manifests a=b2g-bump