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

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https://hg.mozilla.org/integration/gaia-central/rev/230007bd85e7
Author: Dave Hunt <dave.hunt@gmail.com>
Desc: Bug 963301 - Bump marionette_client dependency to 0.7.3. r=fstrugariu

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https://hg.mozilla.org/integration/gaia-central/rev/716fb312118d
Author: Jose Antonio Olivera Ortega <josea.olivera@gmail.com>
Desc: Merge pull request #15726 from jaoo/962912

Bug 962912 - Custom APN fail to apply if default APN does not exist. r=kaze

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https://hg.mozilla.org/integration/gaia-central/rev/67daea37f473
Author: Jose Antonio Olivera Ortega <josea.olivera@gmail.com>
Desc: Bug 962912 - Custom APN fail to apply if default APN does not exist
Bumping manifests a=b2g-bump