Bumping gaia.json for 2 gaia-central revision(s)

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https://hg.mozilla.org/integration/gaia-central/rev/f73524b341f0
Author: gasolin <gasolin@gmail.com>
Desc: Merge pull request #11092 from gasolin/issue-896347

Bug 896347 - typo of apps@1.5x/@2x assets, r=rex

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https://hg.mozilla.org/integration/gaia-central/rev/cd55dac920f7
Author: gasolin <gasolin@gmail.com>
Desc: Bug 896347 - typo of apps@1.5x/@2x assets