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

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https://hg.mozilla.org/integration/gaia-1_4/rev/74aa3f3e63ea
Author: AndreiH <andrei.hutusoru@softvision.ro>
Desc: Merge pull request #18889 from chirarobert/v1.4_email_uplift

Bug 1003746 - Fix the tap_subject() method of email apps

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https://hg.mozilla.org/integration/gaia-1_4/rev/0aa4223d9362
Author: chirarobert <robert.chira@softvision.ro>
Desc: Bug 1003746 - Fix the tap_subject() method of email apps
Bumping manifests a=b2g-bump