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

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https://hg.mozilla.org/integration/gaia-central/rev/2187e6fbf807
Author: viorelaioia <viorela.ioia@softvision.ro>
Desc: Merge pull request #26591 from chirarobert/bug_1097754

Bug 1097754 - Investigate intermittent failure of test_dialer_receive_ca...

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https://hg.mozilla.org/integration/gaia-central/rev/edbef0a8b916
Author: Robert Chira <robertchira@P5075.(none)>
Desc: Bug 1097754 - Investigate intermittent failure of test_dialer_receive_call_with_locked_screen.py
Bumping manifests a=b2g-bump