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

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https://hg.mozilla.org/integration/gaia-2_1/rev/ec06b8e9dd2c
Author: mai <mri@tid.es>
Desc: Bug 1069157 - [PDF Viewer] update pdf.js in Gaia

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https://hg.mozilla.org/integration/gaia-2_1/rev/7c372489aacd
Author: Manuel Casas <manuel.casasbarrado@telefonica.com>
Desc: Bug 1074051 - [Settings] sound volume is not changed. Patch v2.0
Bumping manifests a=b2g-bump