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

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https://hg.mozilla.org/integration/gaia-central/rev/75333d4c8b68
Author: EragonJ <eragonj@eragonj.me>
Desc: Merge pull request #21860 from EragonJ/bug-1039948

Bug 1039948 - [System::StatusBar] Airplane mode icon update issues

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https://hg.mozilla.org/integration/gaia-central/rev/d20cbe1a69af
Author: EragonJ <eragonj@eragonj.me>
Desc: Bug 1039948 - [System::StatusBar] Airplane mode icon update issues
Bumping manifests a=b2g-bump