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

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https://hg.mozilla.org/integration/gaia-central/rev/817c28709daf
Author: Ben Francis <ben@tola.me.uk>
Desc: Merge pull request #11945 from RudyLu/Bug912906_extend_timeout_forBrowserDBTest

 Bug 912906 - Extend the unit test timeout to 5 seconds for r=benfrancis

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https://hg.mozilla.org/integration/gaia-central/rev/4d879c638593
Author: Rudy Lu <left.lu@gmail.com>
Desc:  Bug 912906 - Extend the unit test timeout to 5 seconds for
 browser_db_test.