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

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https://hg.mozilla.org/integration/gaia-central/rev/64e6ed57b1b9
Author: Fernando Campo <fernando.campo@o2.com>
Desc: Merge pull request #12983 from fcampo/ftu_navigation-tests-fix

Fix and update navigation tests (r=jmcf)

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https://hg.mozilla.org/integration/gaia-central/rev/2ca4fea6b08e
Author: Fernando Campo <fernando.campo@o2.com>
Desc: Fix and update navigation tests