Bumping gaia.json for 2 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/5991ff136cef
Author: Germán Toro del Valle <gtorodelvalle@gmail.com>
Desc: Merge pull request #24468 from gtorodelvalle/emergency-call-bug-1060730-use-promise-all

Bug 1060730 - Turn updateICEContacts() into a Promise.all() barrier

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https://hg.mozilla.org/integration/gaia-central/rev/4e04a7b6e3b1
Author: German Toro del Valle <gtorodelvalle@gmail.com>
Desc: Bug 1060730 - Turn updateICEContacts() into a Promise.all() barrier
Bumping manifests a=b2g-bump