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

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https://hg.mozilla.org/integration/gaia-1_3/rev/a9ff9320267e
Author: Ryan VanderMeulen <rvandermeulen@mozilla.com>
Desc: Merge pull request #19163 from azasypkin/v1.3-fix-activity-picker-tests

Bug 999286 - [Sora][Message]The content is lost after do some operations. Fixed ActivityPicker tests. r=julien a=tests

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https://hg.mozilla.org/integration/gaia-1_3/rev/713061aafb41
Author: Aleh Zasypkin <azasypkin@mozilla.com>
Desc: Bug 999286 - [Sora][Message]The content is lost after do some operations. Fixed ActivityPicker tests. r=julien a=tests
Bumping manifests a=b2g-bump
Merge b2g28 to v1.3t. a=merge