Bumping gaia.json for 1 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/296ce79d8917
Author: Anthony Ricaud <anthony@ricaud.me>
Desc: Revert "Bug 969280 - disabling all navigation bar tests in dialer for tbpl bustage"

This reverts commit 22d48b62df7901ad45044f66e15e7d8943884a06.
Bumping manifests a=b2g-bump