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

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https://hg.mozilla.org/integration/gaia-central/rev/3fa9e9abfc60
Author: Etienne Segonzac <etienne@segonzac.info>
Desc: Merge pull request #18217 from etiennesegonzac/bug-993807-network-initiated-mmi

Bug 993807 - Making sure the MmiManager is initialized for network initiated MMI sessions. r=rik

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https://hg.mozilla.org/integration/gaia-central/rev/3ba204c17bfe
Author: Etienne Segonzac <etienne@segonzac.info>
Desc: Bug 993807 - Making sure the MmiManager is initialized for network initiated MMI sessions.
Bumping manifests a=b2g-bump