remove gotest.tools dependency

[thaJeztah]

• alternative to / closes https://github.com/moby/ipvs/pull/28
• relates to https://github.com/kubernetes/kubernetes/issues/114942

[dims]

I prefer this as we completely eliminate 2 packages (as opposed to the PR https://github.com/moby/ipvs/pull/28)

[thaJeztah]

I prefer this as we completely eliminate 2 packages (as opposed to the PR #28)

Yup, same.

Also eyeing logrus, but it appears to be used in quite a few places, so perhaps that's for a later concern.

I do want to have a quick look at;

• updating GitHub actions to test against current versions (we can keep 1.13 as "oldest" version in the matrix; probably no harm
• update golangci-lint (probably needed if we update go versions)
• update the golang.org/x/sys to a tagged release, and update logrus to get old versions out of the dependency tree

[thaJeztah]

@cpuguy83 PTAL 🤗

[pacoxu]

Great work.