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

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https://hg.mozilla.org/integration/gaia-2_1/rev/37814031c0d3
Author: Ryan VanderMeulen <ryanvm@gmail.com>
Desc: Merge pull request #26223 from gitmai/bug-1069157-pdfviewer-update

Bug 1069157 - [PDF Viewer] update pdfj.js in Gaia for v2.1

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https://hg.mozilla.org/integration/gaia-2_1/rev/d88f60c62540
Author: mai <mri@tid.es>
Desc: Bug 1069157 - [PDF Viewer] update pdfj.js in Gaia for v2.1
Bumping manifests a=b2g-bump