talks: Fix misleading constant expression in taste.slide
talks: Fix misleading constant expression in taste.slide

The current text has "third=1/3", but 1/3 = 0. Make it 1.0/3 instead.

Change-Id: I19ea0e7ceb73b5526f53d62aa4308c8530d4eae6
Reviewed-on: https://go-review.googlesource.com/8162
Reviewed-by: Robert Griesemer <a6752097faebf1f02d80107d77a9be009089afe3@golang.org>

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