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

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https://hg.mozilla.org/integration/gaia-central/rev/4c4ffe7f2c16
Author: Dave Hylands <dhylands@gmail.com>
Desc: Merge pull request #24236 from dhylands/bug-1059484-enable-sdcard1

Bug 1059484 - Enable sharing on the external storage card called sdcard1...

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https://hg.mozilla.org/integration/gaia-central/rev/64a7678f2e6b
Author: Dave Hylands <dhylands@gmail.com>
Desc: Bug 1059484 - Enable sharing on the external storage card called sdcard1. r=arthur.chen
Bumping manifests a=b2g-bump