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

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https://hg.mozilla.org/integration/gaia-central/rev/6d1addb30556
Author: Gareth Aye <gaye@mozilla.com>
Desc: Merge pull request #14860 from gaye/bug-952168

Bug 952168 - Edges gestures tests are failing on TBPL

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https://hg.mozilla.org/integration/gaia-central/rev/9ec730114e20
Author: Gareth Aye <gaye@mozilla.com>
Desc: Bug 952168 - Edges gestures tests are failing on TBPL