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

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https://hg.mozilla.org/integration/gaia-central/rev/b1747268be1d
Author: chirarobert <robert.chira@softvision.ro>
Desc: Merge pull request #24425 from viorelaioia/camera_flash

Bug 1072343 - Improve wait in test_camera_flash_modes.py

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https://hg.mozilla.org/integration/gaia-central/rev/fc2064aec177
Author: Viorela Ioia <viorelaioia@gmail.com>
Desc: Bug 1072343 - Improve wait in test_camera_flash_modes.py
Bumping manifests a=b2g-bump