Bumping gaia.json for 6 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/8b94c3c007f7
Author: vingtetun <21@vingtetun.org>
Desc: Merge pull request #16963 from vingtetun/bug980417

Bug 980417 - The call log headers are transparent on the side. r=Rik

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https://hg.mozilla.org/integration/gaia-central/rev/4f059db450cc
Author: Vivien Nicolas <21@vingtetun.org>
Desc: Bug 980417 - The call log headers are transparent on the side. r=Rik

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https://hg.mozilla.org/integration/gaia-central/rev/776f43918207
Author: Ryan VanderMeulen <rvandermeulen@mozilla.com>
Desc: Merge pull request #16752 from yzen/957674

Bug 957674 - switching the screen reader toggle sequence from power butt...

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https://hg.mozilla.org/integration/gaia-central/rev/a01c7caa0b4b
Author: Yura Zenevich <yzenevich@mozilla.com>
Desc: Bug 957674 - switching the screen reader toggle sequence from power button to volume up/down buttons.

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https://hg.mozilla.org/integration/gaia-central/rev/75537ed270ba
Author: Marcus Cavanaugh <m@mcav.com>
Desc: Merge pull request #16858 from mcav/translate-timer-sound-panel

Bug 979492 - [B2G][Clock][Timer]Missing titles in sound selection list. r=millermedeiros

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https://hg.mozilla.org/integration/gaia-central/rev/6541934fefce
Author: Marcus Cavanaugh <m@mcav.com>
Desc: Bug 979492 - [B2G][Clock][Timer]Missing titles in sound selection list for timer
Bumping manifests a=b2g-bump