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

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https://hg.mozilla.org/integration/gaia-central/rev/020cc128dbe2
Author: Douglas Sherk <github@sherk.me>
Desc: Merge pull request #23431 from tamarahills/bugfix/1035763

Bug 1035763 - Support 24 hour time format. r=drs

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https://hg.mozilla.org/integration/gaia-central/rev/18804d7f2549
Author: Tamara Hills <thills@mozilla.com>
Desc: Bug 1035763 -- Support 24 hour time format. r=drs.
Bumping manifests a=b2g-bump