Bumping gaia.json for 3 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/5d00248220fd
Author: Zac Campbell <zcampbell@mozilla.com>
Desc: Bug 964918 - Fix timing in Python test_kill_multiple r=me a=testonly

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https://hg.mozilla.org/integration/gaia-central/rev/a8d960b37f12
Author: Hubert Figuière <hub@figuiere.net>
Desc: Merge pull request #16092 from hfiguiere/bug962040-2

Bug 962040 - blacklist camera until we figure out why it hangs. r=julienw

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https://hg.mozilla.org/integration/gaia-central/rev/4a8dd3152582
Author: Hubert Figuière <hub@figuiere.net>
Desc: Bug 962040 - blacklist camera until we figure out why it hangs.
Bumping manifests a=b2g-bump