📌 Pin viper module to v1.12.0 in go.mod

I've been trying to get `golangci-lint` to work with `go tool`. The only
issue I've run into so far is related to dependency versions.

I'm importing the `golangci-lint` module into a module that also imports
`viper`. However, while `golangci-lint` imports `v1.12.0`, my module
imports `v1.19.0` (the latest version). When I run `go tool golangci-lint`
the Go compiler compiles `golangci-lint` with `[email protected]`, which
breaks part of the `revive` linter (see issue #3280). It possibly breaks
parts of other linters, but my specific configuration did not reveal it.

I'm currently working around this by removing the configuration that
`golangci-lint` can't handle when using `[email protected]`. However I
believe we can get the Go compiler to use `[email protected]` for
`golangci-lint` and whatever other version for any module that would
import `golangci-lint`. The trick is to add a replacement to
`golangci-lint`'s `go.mod`:

```gomod
replace github.com/spf13/viper => github.com/spf13/viper v1.12.0
```

I've experimented with this fix by using Go workspaces and it seems to
work as desired. The parent module can still use `[email protected]` and
the issue in the `revive` linter does not occur.

This change requires disabling the `gomoddirectives` linter in a couple
of `golangci-lint`'s tests. Those tests are completely unrelated to that
specific linter or to `go.mod`, so I figure it's fine.

Author: busser

go.mod

@@ -135,6 +135,14 @@ require (
 	mvdan.cc/unparam v0.0.0-20240528143540-8a5130ca722f
 )
 
+// When another module imports golangci-lint, they may require a version of
+// Viper above 1.12.0. The Go compiler will then use the higher version, which
+// will break golangci-lint. This replacement ensures that golangci-lint uses
+// the version it requires without impacting modules that import golangci-lint.
+// See https://github.com/golangci/golangci-lint/issues/3280 for details on why
+// golangci-lint is pinned to Viper 1.12.0.
+replace github.com/spf13/viper => github.com/spf13/viper v1.12.0
+
 require (
 	github.com/Masterminds/semver/v3 v3.3.1 // indirect
 	github.com/aymanbagabas/go-osc52/v2 v2.0.1 // indirect

test/run_test.go

@@ -129,6 +129,8 @@ func TestCgoOk(t *testing.T) {
 			"--timeout=3m",
 			"--show-stats=false",
 			"--default=all",
+			// We need to disable gomoddirectives because it fails on our own go.mod.
+			"--disable=gomoddirectives",
 		).
 		WithTargetPath(testdataDir, "cgo").
 		Runner().
@@ -345,6 +347,8 @@ linters:
 		WithArgs(
 			"--show-stats=false",
 			"--default=all",
+			// We need to disable gomoddirectives because it fails on our own go.mod.
+			"--disable=gomoddirectives",
 		).
 		WithTargetPath(testdataDir, "unsafe").
 		WithBinPath(binPath).