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

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https://hg.mozilla.org/integration/gaia-central/rev/51051a09cdd5
Author: Dominic Kuo <dkuo@mozilla.com>
Desc: Merge pull request #26953 from dominickuo/bug-1092969

Bug 1092969 - [Music] only enable the text selection in the tiles and list search inputs, r=jimporter

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https://hg.mozilla.org/integration/gaia-central/rev/29560fe9d77f
Author: Dominic Kuo <dkuo@mozilla.com>
Desc: Bug 1092969 - [Music] only enable the text selection in the tiles and list search inputs
Bumping manifests a=b2g-bump