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

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https://hg.mozilla.org/integration/gaia-central/rev/3d37154ba2e4
Author: Zac <zcampbell@mozilla.com>
Desc: Merge pull request #16523 from bobsilverberg/stop_exception

Bug 972557 - To address Bug 971747 - Add an exception that will report when b2g cannot be stopped

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https://hg.mozilla.org/integration/gaia-central/rev/69f95ae486a8
Author: Bob Silverberg <bob.silverberg@gmail.com>
Desc: Bug 972557 - To address Bug 971747 - Add an exception that will report when b2g cannot be stopped
Bumping manifests a=b2g-bump