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

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https://hg.mozilla.org/integration/gaia-central/rev/c4d102a23136
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #16076 from KevinGrandon/bug_969287_keyboard_sound

Bug 969287 - Keyboard click sound should not be enabled by default r=janjongboom

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https://hg.mozilla.org/integration/gaia-central/rev/bbb7809c1eff
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 969287 - Keyboard click sound should not be enabled by default r=janjongboom

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https://hg.mozilla.org/integration/gaia-central/rev/6b9bbdd9a3e6
Author: Zac <zcampbell@mozilla.com>
Desc: Merge pull request #16042 from AndreiH/bug968794

Bug 968794 - Test test_settings_do_not_track fails intermittently on dev...

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https://hg.mozilla.org/integration/gaia-central/rev/ea2054d85fe0
Author: Andrei Hutusoru <andreihutusoru@P5069.(none)>
Desc: Bug 968794 - Test test_settings_do_not_track fails intermittently on device
Bumping manifests a=b2g-bump