Update golang versions

[jodh-intel]

The versions database currently specifies:

$ yq read versions.yaml languages.golang.version
1.10.4
$ yq read versions.yaml languages.golang.meta.newest-version
1.11.1

FWICS...

• The snap build is using golang 1.10.4:

  https://github.com/kata-containers/packaging/blob/master/snap/snapcraft.yaml#L16

• The packaging is using golang 1.11.1:

  https://github.com/kata-containers/packaging/blob/master/obs-packaging/gen_versions_txt.sh#L49

• The CI system is using golang 1.11.1:

  https://github.com/kata-containers/tests/blob/master/.ci/install_go.sh#L79

However, from https://golang.org/dl:

• The latest stable golang is now: 1.12.
• The oldest stable golang version is now: 1.11.5

TL;DR

We should consider updating golang versions to:

languages.golang.version = 1.11.5
languages.golang.meta.newest-version = 1.12

Related to discussions about go mod (#1331).

/cc @chavafg.