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

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https://hg.mozilla.org/integration/gaia-central/rev/55c5e5ee283e
Author: Francisco Jordano <arcturus@ardeenelinfierno.com>
Desc: Merge pull request #22311 from arcturus/bug-1045503

Bug 1045503 - [tarako][contacts] we should reduce the use of storage by contacts app r=jmcf

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https://hg.mozilla.org/integration/gaia-central/rev/6d0a183870cb
Author: Francisco Jordano <fjordano@mozilla.com>
Desc: Bug 1045503 - [tarako][contacts] we should reduce the use of storage by contacts app
Bumping manifests a=b2g-bump