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

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https://hg.mozilla.org/integration/gaia-2_0/rev/76e9e37b866e
Author: Ryan VanderMeulen <ryanvm@gmail.com>
Desc: Merge pull request #25033 from eliperelman/bug-1080812-v2.0

Bug 1080812 - Fixing performance test issue with screen timeouts

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https://hg.mozilla.org/integration/gaia-2_0/rev/8ab997618253
Author: Eli Perelman <eli@eliperelman.com>
Desc: Bug 1080812 - Fixing performance test issue with screen timeouts
Bumping manifests a=b2g-bump