golang1.21 + slog

[thepwagner]

log/slog is pretty good.

For all the logging we do, let's migrate to the stdlib and trim some dependencies.

[jacobmichels]

A welcome addition to the stdlib!

[jacobmichels]

Why disable some linting?

[thepwagner]

Sorry - I missed that in the PR description!

3/4, because they're deprecated and we're using the "replaced by X" linter already. This removes a warning on startup.

WARN [runner] The linter 'deadcode' is deprecated (since v1.49.0) due to: The owner seems to have abandoned the linter. Replaced by unused.
WARN [runner] The linter 'structcheck' is deprecated (since v1.49.0) due to: The owner seems to have abandoned the linter. Replaced by unused.
WARN [runner] The linter 'varcheck' is deprecated (since v1.49.0) due to: The owner seems to have abandoned the linter. Replaced by unused.

---

The weirder one was depguard:

internal/cli/app.go:4:2: import 'github.com/go-logr/logr' is not allowed from list 'Main' (depguard)
	"github.com/go-logr/logr"
	^
internal/cli/app.go:5:2: import 'github.com/urfave/cli/v2' is not allowed from list 'Main' (depguard)
	"github.com/urfave/cli/v2"
	^
internal/cli/generate.go:10:2: import 'github.com/go-logr/logr' is not allowed from list 'Main' (depguard)
	"github.com/go-logr/logr"
	^
internal/cli/generate.go:11:2: import 'github.com/goreleaser/nfpm/v2' is not allowed from list 'Main' (depguard)
	"github.com/goreleaser/nfpm/v2"
	^

and it seems to repeat that for every imported dependency.

From the error description, I assumed it depguard's configuration had moved from a "denylist" approach where we list the naughty packages we don't want, to an "allowlist" approach where we need to specify the packages we like.
I didn't find golangci/golangci-lint#3906 until you asked, but it aligns with that assumption 😎 . Since we're upgrading from 1.51 to 1.55, we have to clear the hurdles from 1.53.

I figured since we weren't giving depguard a naughty OR a nice list, it wasn't doing much. Yeet.

[thepwagner]

I appreciate the irony that depguard would be useful to say... encode that github.com/rs/zerolog should be avoided and we'd prefer you to use log/slog instead.