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

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https://hg.mozilla.org/integration/gaia-2_0/rev/f4818dc8b7ce
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #21308 from KevinGrandon/bug_1033632_collection_user_select

Bug 1033632 - [Collections] Highlight on all app title occurs when tapping on a title of an app

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https://hg.mozilla.org/integration/gaia-2_0/rev/81cd4fae1689
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #21270 from Cwiiis/bug1031094-squashed

Bug 1031094 - Don't remove bookmarks from collections when uninstalling. r=kgrandon

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https://hg.mozilla.org/integration/gaia-2_0/rev/4f645c68c982
Author: James Burke <jrburke@gmail.com>
Desc: Merge pull request #21297 from jrburke/bug911412-email-view-icon

Bug 911412 - [Buri][fugu][Language][Email]The view the attachment Button is truncated r=jrburke

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https://hg.mozilla.org/integration/gaia-2_0/rev/87f55242bbca
Author: Arnau <arnau@arnaumarch.com>
Desc: Merge pull request #20796 from pacorampas/call-screen-space-name-number-1026341

Bug 1026341 - [Dialer][Call Screen][Flame] Some space, a thin line, not covered by name, number white background r=rik
Bumping manifests a=b2g-bump