Bumping gaia.json for 1 gaia-1_3 revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-1_3/rev/4cf7d74e806f
Author: Gabriele Svelto <gsvelto@mozilla.com>
Desc: Bug 960280 - Generate canvases that are not displayed with the appropriate tag to reduce memory usage r=arcturus

(cherry picked from commit 5df7622aa7456415503dc374a9b80a5fce40dc58)