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

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https://hg.mozilla.org/integration/gaia-central/rev/37cd9a62b2cb
Author: Rudy Lu <me@rudy.lu>
Desc: Merge pull request #20259 from RudyLu/ringtone/Bug1023045-Sound_backButton

Bug 1023045 - [Settings][Ringtone][V2.0] The "<" icon of
 r=jimporter.

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https://hg.mozilla.org/integration/gaia-central/rev/65e582e46a6f
Author: Rudy Lu <me@rudy.lu>
Desc:  Bug 1023045 - [Settings][Ringtone][V2.0] The "<" icon of
 sound settings page becomes "X" icon after back from ringtone app.
  - Don't specify "section" when invoking the settings app activity.

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https://hg.mozilla.org/integration/gaia-central/rev/8542b2ac300b
Author: Carmen Jiménez <cjc@tid.es>
Desc: Merge pull request #20218 from mcjimenez/bug1022513

Bug 1022513 - Add unit tests for the vertical homescreen configuration
r=kgrandon

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https://hg.mozilla.org/integration/gaia-central/rev/77221c5db45d
Author: Carmen Jimenez Cabezas <cjc@tid.es>
Desc: Bug 1022513 - Add unit tests for the vertical homescreen configuration
Bumping manifests a=b2g-bump