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

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https://hg.mozilla.org/integration/gaia-central/rev/897ebc324cd5
Author: Bob Silverberg <bob.silverberg@gmail.com>
Desc: Merge pull request #13388 from zacc/bug_935041

Bug 935041 - Investigate test_sms_add_contact failure, resolve and re-en...

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https://hg.mozilla.org/integration/gaia-central/rev/bfe3328d3051
Author: Zac Campbell <zcampbell@mozilla.com>
Desc: Bug 935041 - Investigate test_sms_add_contact failure, resolve and re-enable the test