Bumping gaia.json for 1 gaia revision(s) a=gaia-bump

========

https://hg.mozilla.org/integration/gaia-1_4/rev/551773b4acf8
Author: David Flanagan <dflanagan@mozilla.com>
Desc: Merge pull request #19956 from davidflanagan/bug996455

Bug 996455: use device pixels, not css pixels when determining if an EXIF preview is big enough r=pdahiya a=1.3+,hkoka
Bumping manifests a=b2g-bump