CI: fix release builds

[johanbrandhorst]

For some reason running "go mod vendor" edited the sum file.
Lets make sure there are no more surprises by running it in
CI as well.

Fixes #886

[johanbrandhorst]

MUST NOT BE MERGED AS IS

[johanbrandhorst]

I rebuilt the build environment image with go 1.12 which explains some of the other errors.

[johanbrandhorst]

Gonna leave the updating of the build environment for another PR.

[codecov-io]

Codecov Report

Merging #884 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #884   +/-   ##
=======================================
  Coverage   53.69%   53.69%           
=======================================
  Files          39       39           
  Lines        3926     3926           
=======================================
  Hits         2108     2108           
  Misses       1621     1621           
  Partials      197      197

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[thepudds]

This looks good from very quick look.

One thing you could do to help test it before going 'live' is to first tag it with a semver prerelease tag like v1.8.1-pre1, which means someone can use that as part of a go get github.com/grpc-ecosystem/grpc-gateway@v1.8.1-pre1, but it won't yet be live for someone that does not use the prelease tag.

[johanbrandhorst]

This looks good from very quick look.

One thing you could do to help test it before going 'live' is to first tag it with a semver prerelease tag like v1.8.1-pre1, which means someone can use that as part of a go get github.com/grpc-ecosystem/grpc-gateway@v1.8.1-pre1, but it won't yet be live for someone that does not use the prelease tag.

Excellent idea, I shall action that as soon as I've merged this.