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

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https://hg.mozilla.org/integration/gaia-central/rev/31de4f8fa28c
Author: Zibi Braniecki <zbigniew.braniecki@gmail.com>
Desc: Merge pull request #23157 from zbraniecki/1055328-embed-net_error-strings

Bug 1055328 - Embed all l10n resources in net_error.html. r=yurenyu

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https://hg.mozilla.org/integration/gaia-central/rev/4f883ab56e51
Author: Zbigniew Braniecki <gandalf@mozilla.com>
Desc: Bug 1055328 - Embed all l10n resources in net_error.html
Bumping manifests a=b2g-bump