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

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https://hg.mozilla.org/integration/gaia-central/rev/50e3fd1c57d2
Author: Jose M. Cantera <jmcanterafonseca@gmail.com>
Desc: Merge pull request #23758 from ADLR-es/fix-bug-1060101

Bug 1060101 - [Settings][Facebook] Removing a Facebook account from Cont...

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https://hg.mozilla.org/integration/gaia-central/rev/6636dea291f3
Author: Adrián de la Rosa <hola@adlr.es>
Desc: Bug 1060101 - [Settings][Facebook] Removing a Facebook account from Contacts will not finish if Facebook was set up during the FTU / FTE
Bumping manifests a=b2g-bump