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

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https://hg.mozilla.org/integration/gaia-central/rev/75423c872bf4
Author: Anthony Ricaud <anthony@ricaud.me>
Desc: Merge pull request #10486 from Rik/deleted-files-884592

Bug 884592 - Only lint existing files in the pre-commit hook r=vingtetun

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https://hg.mozilla.org/integration/gaia-central/rev/a0d0d891a524
Author: Anthony Ricaud <anthony@ricaud.me>
Desc: Bug 884592 - Only lint existing files in the pre-commit hook