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

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https://hg.mozilla.org/integration/gaia-central/rev/9d7eb000470a
Author: Timothy Guan-tin Chien <timdream@gmail.com>
Desc: Merge pull request #23017 from timdream/keyboard-remove-demo-keyboard

Bug 1055398 - Remove demo-keyboard from eng build, r=rudyl

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https://hg.mozilla.org/integration/gaia-central/rev/6d93f59cb1ad
Author: Timothy Guan-tin Chien <timdream@gmail.com>
Desc: Bug 1055398 - Remove demo-keyboard from eng build

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https://hg.mozilla.org/integration/gaia-central/rev/de95a3101ea3
Author: Yuren Ju <yurenju@gmail.com>
Desc: Merge pull request #22774 from yurenju/app-makefile-2

Bug 1029385 - Rewrite app-makefile rule in javascript

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https://hg.mozilla.org/integration/gaia-central/rev/71a3013157a8
Author: Yuren Ju <yurenju@gmail.com>
Desc: Bug 1029385 - Rewrite app-makefile rule in javascript r=ochameau

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https://hg.mozilla.org/integration/gaia-central/rev/4269d6dc74a7
Author: Pavel Ivanov <pivanov@mozilla.com>
Desc: Merge pull request #22718 from pivanov/bug-1044274

Bug 1044274 - [Gallery][RTL] gallery image view back button is not RTL

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https://hg.mozilla.org/integration/gaia-central/rev/272091020f0d
Author: Pavel Ivanov <pivanov@mozilla.com>
Desc: Bug 1044274 - [Gallery][RTL] gallery image view back button is not RTL r=pdahiya
Bumping manifests a=b2g-bump