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

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https://hg.mozilla.org/integration/gaia-central/rev/b408bfc1fdeb
Author: Fernando Rodríguez Sela <frsela@tid.es>
Desc: Merge pull request #23114 from davidflanagan/bug1054953

Bug 1054953: make the FL app handle the incorrect audio/mp3 mime type, r=amac

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https://hg.mozilla.org/integration/gaia-central/rev/ebaa23f5ff0e
Author: David Flanagan <dflanagan@mozilla.com>
Desc: Bug 1054953: make the FL app handle the incorrect audio/mp3 mime type
Bumping manifests a=b2g-bump