fix: remove usage of deprecated Type attribute of resolver.Address

[KnutZuidema]

The type attribute has been removed in more recent versions of gRPC. The usage here is not required and the may be removed.

See: grpc/grpc-go#6451
As mentioned in: #30 (comment)

[dannyskoog]

@KnutZuidema Probably makes sense to bump google.golang.org/grpc to the latest version as well. Plus remove the following line: https://github.com/sercand/kuberesolver/blob/master/builder_test.go#L44

[KnutZuidema]

@dannyskoog agreed, however I'd prefer getting this immediately broken line fixed and then fixing the rest separately. I don't know what @sercand prefers. In the end I'm fine with either.

[dannyskoog]

@KnutZuidema Fair enough! Let's have @sercand decide that then

[sercand]

@KnutZuidema Thanks for the PR. I think @dannyskoog is right, we should remove other usages of ".Type" in the repo but the version can stay same.

[KnutZuidema]

@sercand will close this PR and open another since using the master branch in my fork doesn't allow me to amend the requested addition into the existing commit.