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

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https://hg.mozilla.org/integration/gaia-central/rev/8c1ff28d0df6
Author: Miller Medeiros <miller@millermedeiros.com>
Desc: Merge pull request #17301 from millermedeiros/969472-event-tap-disable

Bug 969472 - [B2G][Calendar] Events can still be tapped on and viewed when no calendar accounts are activated r=gaye

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https://hg.mozilla.org/integration/gaia-central/rev/5b5bd9a2725d
Author: Miller Medeiros <miller@millermedeiros.com>
Desc: Bug 969472 - [B2G][Calendar] Events can still be tapped on and viewed when no calendar accounts are activated
Bumping manifests a=b2g-bump