Bumping gaia.json for 3 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-2_0/rev/028871514bda
Author: Gabriele Svelto <gsvelto@mozilla.com>
Desc: Merge pull request #21538 from gabrielesvelto/bug-1016885-v2.0-uplift

Bug 1016885 - v2.0 uplift

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https://hg.mozilla.org/integration/gaia-2_0/rev/ea64b5129cd3
Author: Gabriele Svelto <gsvelto@mozilla.com>
Desc: Bug 1016885 - Always initialize the MmiManager before sending a notification r=etienne

(cherry picked from commit c664153cd702ae1db12a485e539bae88b9bdcdea)

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https://hg.mozilla.org/integration/gaia-2_0/rev/2e6cc21eb740
Author: Gabriele Svelto <gsvelto@mozilla.com>
Desc: Bug 1016885 - Send a notification instead of displaying the dialer when receiving an unsolicited USSD notification r=etienne

(cherry picked from commit ddbf0e11b494fd9665545141485d0b70cab6d514)
Bumping manifests a=b2g-bump