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

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https://hg.mozilla.org/integration/gaia-central/rev/de7d1d59e942
Author: Anthony Ricaud <anthony@ricaud.me>
Desc: Revert "Revert "Merge pull request #14667 from mcav/utf7""

This reverts commit 7852023abb572c522a07af558e7c19f557cc4866.

That was a wrong revert, it didn't fix the failing tests.