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

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https://hg.mozilla.org/integration/gaia-central/rev/de236fe500ab
Author: Julien Wajsberg <felash@gmail.com>
Desc: Merge pull request #18222 from julienw/993961-fix-camera-test-b2g

Bug 993961 - [Camera] Fix unit tests in B2G Desktop r=dmarcos

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https://hg.mozilla.org/integration/gaia-central/rev/d4070000a902
Author: Julien Wajsberg <julien@mozilla.com>
Desc: Bug 993961 - [Camera] Fix unit tests in B2G Desktop r=dmarcos

Introduces a Audio mock so that we're not affected by the platform differences.
Bumping manifests a=b2g-bump