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

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https://hg.mozilla.org/integration/gaia-central/rev/8b445f90aa40
Author: AndreiH <andrei.hutusoru@softvision.ro>
Desc: Merge pull request #17073 from zacc/bug_979914

Bug 997673 - Refactor of cost control python tests

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https://hg.mozilla.org/integration/gaia-central/rev/6423b5c63f24
Author: Zac <zcampbell@mozilla.com>
Desc: Bug 997673 - Small refactor of Python cost control app tests
Bumping manifests a=b2g-bump