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

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https://hg.mozilla.org/integration/gaia-central/rev/194aa7d5312b
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #23012 from KevinGrandon/bug_1001090_update_gaia_test_let_usage

Bug 1001090 - Update let usage in gaia ui test

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https://hg.mozilla.org/integration/gaia-central/rev/f3979a68ab22
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 1001090 - Update let usage in gaia ui test r=kgrandon r=shu
Bumping manifests a=b2g-bump