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

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https://hg.mozilla.org/integration/gaia-central/rev/b69352905f49
Author: Germán Toro del Valle <gtorodelvalle@gmail.com>
Desc: Merge pull request #15799 from gtorodelvalle/contacts-bug-965168-exporting-to-sd

Bug 965168 - [Contacts] Export contacts to SD card is not working

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https://hg.mozilla.org/integration/gaia-central/rev/079f68e04aa1
Author: Germán Toro del Valle <gtorodelvalle@gmail.com>
Desc: Bug 965168 - [Contacts] Export contacts to SD card is not working

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https://hg.mozilla.org/integration/gaia-central/rev/ac01081c5048
Author: Gregor Wagner <anygregor@gmail.com>
Desc: Merge pull request #15791 from gregorwagner/disable

Bug 965083 - Disable failing unit tests for a green tbpl.

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https://hg.mozilla.org/integration/gaia-central/rev/5525b0d650f8
Author: Gregor Wagner <anygregor@gmail.com>
Desc: Disable failing unit tests
Bumping manifests a=b2g-bump