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

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https://hg.mozilla.org/integration/gaia-central/rev/8452ee537f07
Author: Ryan VanderMeulen <rvandermeulen@mozilla.com>
Desc: Merge pull request #18804 from arky/Fulah-FxOS-Keyboard

Bug 1001363 - Add Fulah / Pulaar-Fulfulde (ff) input method for Gaia

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https://hg.mozilla.org/integration/gaia-central/rev/e157fde4d561
Author: Arky <hitmanarky@gmail.com>
Desc: Bug 1001363 - Add Fulah / Pulaar-Fulfulde (ff) input method for Gaia

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https://hg.mozilla.org/integration/gaia-central/rev/50a7f158dcf7
Author: Cristian Rodriguez <crdlc@tid.es>
Desc: Merge pull request #18826 from crdlc/bug-1003752

Bug 1003752 - [VR][Contacts] Select all and Deselect all buttons shouldn...

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https://hg.mozilla.org/integration/gaia-central/rev/5235d3241cf3
Author: crdlc <crdlc@tid.es>
Desc: Bug 1003752 - [VR][Contacts] Select all and Deselect all buttons shouldnt appear in Delete contacts screen
Bumping manifests a=b2g-bump