Bumping gaia.json for 4 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/12d5e1052238
Author: Aleh Zasypkin <aleh.zasypkin@gmail.com>
Desc: Merge pull request #24275 from azasypkin/bug-1070890-compose-event-dispatcher

Bug 1070890 - [Messages][Refactoring] Make use of EventDispatcher in Compose. r=schung

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https://hg.mozilla.org/integration/gaia-central/rev/7f0b094f53e0
Author: Aleh Zasypkin <azasypkin@mozilla.com>
Desc: Bug 1070890 - [Messages][Refactoring] Make use of EventDispatcher in Compose. r=schung

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https://hg.mozilla.org/integration/gaia-central/rev/98b8780b730e
Author: Zac <zcampbell@mozilla.com>
Desc: Merge pull request #24181 from bebef1987/camera1

Bug 1068722 - Update camera tests to check if the switch source action h...

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https://hg.mozilla.org/integration/gaia-central/rev/46a00019791b
Author: Bebe <bebe@mozilla.ro>
Desc: Bug 1068722 - Update camera tests to check if the switch source action had happen
Bumping manifests a=b2g-bump