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

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https://hg.mozilla.org/integration/gaia-central/rev/6e7cca661d99
Author: Etienne Segonzac <etienne@segonzac.info>
Desc: Merge pull request #17198 from etiennesegonzac/bug-983626-dialer-ringer-followup

Bug 983626 - DialerRinger follow up. r=vingtetun

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https://hg.mozilla.org/integration/gaia-central/rev/129ef795b93e
Author: Etienne Segonzac <etienne@segonzac.info>
Desc: Bug 983626 - DialerRinger follow up. r=vingtetun
Bumping manifests a=b2g-bump