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

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https://hg.mozilla.org/integration/gaia-1_4/rev/37e2ddb50268
Author: Andrew Sutherland <asutherland@asutherland.org>
Desc: Merge pull request #19127 from asutherland/email-update-attachment-status

Bug 1008477 - [email/UI] Virtual list regression; attachment icon only ever gets set never, cleared. Because of DOM node reuse results in misleading attachment icon status. r=jrburke
Bumping manifests a=b2g-bump