Bumping gaia.json for 1 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/3a50d107634e
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 1098310 - Disable intermittent failing test, TEST-UNEXPECTED-FAIL | apps/verticalhome/test/marionette/collection_pin_result_uninstall_test.js | Vertical - Collection uninstall pinned collection web result
Bumping manifests a=b2g-bump