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

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https://hg.mozilla.org/integration/gaia-central/rev/9a608c49a2ef
Author: Ian Liu <iliu@mozilla.com>
Desc: Merge pull request #23887 from ian-liu/settings/bug1057188_l10n_string_revised_for_mount_unmount_sd_card

Bug 1057188 - L10n follow-up for mount/unmount SD card, r=arthur

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https://hg.mozilla.org/integration/gaia-central/rev/87409e71da46
Author: ian-liu <iliu@mozilla.com>
Desc: Bug 1057188 - L10n follow-up for mount/unmount SD card
Bumping manifests a=b2g-bump