Update mkdocs

[porunov]

WIP: Code blocks doesn't work with this update for some reason

Updates mkdocs

Signed-off-by: Oleksandr Porunov [email protected]

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[mbrukman]

@porunov — since your PR says:

WIP: Code blocks doesn't work with this update for some reason

Do you want to convert its status to work-in-progress so it's not merged too soon?