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

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https://hg.mozilla.org/integration/gaia-central/rev/04638bc04c78
Author: vingtetun <21@vingtetun.org>
Desc: Merge pull request #17293 from vingtetun/bug981610-precommit

Bug 981610 - Activate the CSS Linter as a pre-commit hook. r=ochameau

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https://hg.mozilla.org/integration/gaia-central/rev/70f1b12e0a5a
Author: Vivien Nicolas <21@vingtetun.org>
Desc: Bug 981610 - Activate the CSS Linter as a pre-commit hook. r=ochameau
Bumping manifests a=b2g-bump