golangci updates and enable testifylint

This MR updates golangci to the latest stable version (1.55.2) as well as enabling the testifylint linter.

After Workhorse: allow testify/assert (gitlab!137826 - merged) and https://github.com/stretchr/testify/issues/772, I thought we should enable the linter here and run, in the hope it might help internal/command/uploadarchive/uploadarchive_te... (#671) (but there doesn't appear to be any go-require warnings).