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

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https://hg.mozilla.org/integration/gaia-1_4/rev/a6d91a9c7588
Author: Ryan VanderMeulen <rvandermeulen@mozilla.com>
Desc: Merge pull request #23252 from weigao123/Bug1057905-v1.4

Bug 1057905 - [v1.4] Avoid activeApp is null when receiving STK message. r=Tim.

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https://hg.mozilla.org/integration/gaia-1_4/rev/06d0c2ea400d
Author: wei.gao <wei.gao@spreadtrum.com>
Desc: Bug 1057905 - [v1.4] Avoid activeApp is null when receiving STK message. r=Tim.
Bumping manifests a=b2g-bump