Bumping gaia.json for 2 gaia-central revision(s)

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https://hg.mozilla.org/integration/gaia-central/rev/440d939f26d2
Author: Gareth Aye <gaye@mozilla.com>
Desc: Merge pull request #11957 from gaye/bump-marionette-helper

Bump marionette-helper to 0.0.6

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https://hg.mozilla.org/integration/gaia-central/rev/73d18f581157
Author: gaye <gaye@mozilla.com>
Desc: Bump marionette-helper to 0.0.6