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

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https://hg.mozilla.org/integration/gaia-central/rev/61d669984f76
Author: Rex KM Lee <rexboy@mozilla.com>
Desc: Merge pull request #12874 from rexboy7/fix-bug894270

bug 894270 - [Dialer] Display calls following v1.2 spec; switch photo when switching calls. r=rik

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https://hg.mozilla.org/integration/gaia-central/rev/577003db74e6
Author: Rex Lee <rexboy@mozilla.com>
Desc: bug 894270 - [Dialer] switch photos correctly when switching calls.
              Show detail info of participants correctly on multi-calls.