Update dependencies

[tamird]

Testing grpc/grpc-go#1596.

[cockroach-teamcity]

This change is 

[tbg]

but I have not audited the bumped dependencies. Let's leave this open for a few more (work) days.

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Reviewed 1 of 1 files at r1, 1 of 1 files at r2, 8 of 8 files at r3.
Review status: all files reviewed at latest revision, all discussions resolved, some commit checks pending.

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Comments from Reviewable

[bdarnell]

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Reviewed 1 of 1 files at r1, 1 of 1 files at r2, 8 of 8 files at r3.
Review status: all files reviewed at latest revision, all discussions resolved, some commit checks failed.

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Comments from Reviewable