Remove pkg/seed

Since Go 1.20, math/rand does not need explicit seeding:
https://go.dev/doc/go1.20#minor_library_changes

Go <= 1.19 is no longer supported due to EOL.

Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>

cmd/ctr/main.go

@@ -23,15 +23,12 @@ import (
 
 	"github.com/containerd/containerd/v2/cmd/ctr/app"
 	"github.com/containerd/containerd/v2/internal/hasher"
-	"github.com/containerd/containerd/v2/pkg/seed" //nolint:staticcheck // Global math/rand seed is deprecated, but still used by external dependencies
 	"github.com/urfave/cli/v2"
 )
 
 var pluginCmds = []*cli.Command{}
 
 func init() {
-	//nolint:staticcheck // Global math/rand seed is deprecated, but still used by external dependencies
-	seed.WithTimeAndRand()
 	crypto.RegisterHash(crypto.SHA256, hasher.NewSHA256)
 }