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

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https://hg.mozilla.org/integration/gaia-central/rev/88cec5b078eb
Author: Min-Zhong "John" Lu <jlu@mozilla.com>
Desc: Merge pull request #22879 from mnjul/bug_1053613_lockscreen_pin_bckspc_lastrow_vertical_separator

Bug 1053613 - Lockscreen PIN keypad: backspace key misaligned & wrong, vertical separators missing, last row too high. r=gweng

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https://hg.mozilla.org/integration/gaia-central/rev/613fb9e29d20
Author: John Lu [:mnjul] <jlu@mozilla.com>
Desc: Bug 1053613 - Lockscreen PIN keypad: backspace key misaligned & wrong, vertical separators missing, last row too high
Bumping manifests a=b2g-bump