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

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https://hg.mozilla.org/integration/gaia-2_0/rev/7957c2f095e9
Author: Ryan VanderMeulen <rvandermeulen@mozilla.com>
Desc: Merge pull request #21616 from mcjimenez/bug1028789_v2.0

Bug 1028789 - [Sora]There is no character counter inside STK submenus (r = vingtetun)

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https://hg.mozilla.org/integration/gaia-2_0/rev/a35c5ac98b4c
Author: Carmen Jimenez Cabezas <cjc@tid.es>
Desc: Bug 1028789 - [Sora]There is no character counter inside STK submenus
Bumping manifests a=b2g-bump