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

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https://hg.mozilla.org/integration/gaia-2_0/rev/4d2b251fc819
Author: Ghislain 'Aus' Lacroix <aus@noiseport.org>
Desc: Merge pull request #21924 from nullaus/v2.0

Merge pull request #21913 from nullaus/bug1038167

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https://hg.mozilla.org/integration/gaia-2_0/rev/60d8db9782ac
Author: Ghislain 'Aus' Lacroix <aus@noiseport.org>
Desc: Merge pull request #21913 from nullaus/bug1038167

bug 1038167 - Update icons for Find My Device, Vertical Homescreen, Smar...
(cherry picked from commit 8388e81f0a08fb5b71cb2c37dbc3d3366edab61d)
Bumping manifests a=b2g-bump