bump vndr to f5ab8fc5f, and revendor

[thaJeztah]

The latest version of vndr preserves go.mod in vendored dependencies, which makes it easier to check if other dependencies need to be updated as well

- What I did

- How I did it

- How to verify it

- Description for the changelog

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[AkihiroSuda]

22:42:11 The result of vndr differs
22:42:11 
22:42:11  M vendor/github.com/moby/buildkit/go.mod
22:42:11 
22:42:11 Please vendor your package with github.com/LK4D4/vndr.

[thaJeztah]

hm interesting; let me try running it again

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (master@70f67c6). Click here to learn what that means.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master   #39216   +/-   ##
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  Files             ?      609           
  Lines             ?    45197           
  Branches          ?        0           
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  Hits              ?    16868           
  Misses            ?    26040           
  Partials          ?     2289

[thaJeztah]

I have no idea why vendor check is failing; I ran vndr again, but it gave no changes on my machine, but vendor is still failing;

16:48:24 2019/05/17 16:48:24 Running time: 1m29.172936525s
16:48:24 The result of vndr differs
16:48:24 
16:48:24  M vendor/github.com/moby/buildkit/go.mod
16:48:24 
16:48:24 Please vendor your package with github.com/LK4D4/vndr.

It shows M though (modified), so wondering if it's a newline issue, or perhaps whitespace? weird.

[tiborvass]

@thaJeztah I think it just needs a rebase. Hopefully this time it's good!

[tiborvass]

For the record I changed vndr to f5ab8fc5f to include LK4D4/vndr#80