Update linter config, in particular revive

[ldemailly]

          About revive, the default settings are very lame

There is an enable-all equivalent, that should be activated

Here is a golangci-lint .golangci.yml I wrote a few months ago

You can have a look at the revive settings

https://github.com/theredditbandit/pman/blob/master/.golangci.yaml#L133-L219

Originally posted by @ccoVeille in #55 (comment)

[ccoVeille]

This one is also interesting

linters-settings:
  usestdlibvars:
    # Suggest the use of time.Layout.
    # Default: false
    time-layout: true

Originally posted by @ccoVeille in #55 (comment)