Require Go 1.23.x, drop Go 1.22 support

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

go.mod

@@ -1,11 +1,6 @@
 module github.com/opencontainers/runc
 
-go 1.22
+go 1.23.0
-
-// Suggest toolchain 1.22.4 due to a fix in golang for libcontainer/nsenter/.
-// For more info, see: #4233
-// Note that toolchain does not impose a requirement on other modules using runc.
-toolchain go1.22.4
 
 require (
 	github.com/checkpoint-restore/go-criu/v6 v6.3.0

libcontainer/system/rlimit_linux_go122.go

@@ -1,27 +0,0 @@
-//go:build !go1.23
-
-// TODO: remove this file once go 1.22 is no longer supported.
-
-package system
-
-import (
-	"sync/atomic"
-	"syscall"
-	_ "unsafe" // Needed for go:linkname to work.
-)
-
-//go:linkname syscallOrigRlimitNofile syscall.origRlimitNofile
-var syscallOrigRlimitNofile atomic.Pointer[syscall.Rlimit]
-
-// ClearRlimitNofileCache clears go runtime's nofile rlimit cache.
-// The argument is process RLIMIT_NOFILE values.
-func ClearRlimitNofileCache(_ *syscall.Rlimit) {
-	// As reported in issue #4195, the new version of go runtime(since 1.19)
-	// will cache rlimit-nofile. Before executing execve, the rlimit-nofile
-	// of the process will be restored with the cache. In runc, this will
-	// cause the rlimit-nofile setting by the parent process for the container
-	// to become invalid. It can be solved by clearing this cache. But
-	// unfortunately, go stdlib doesn't provide such function, so we need to
-	// link to the private var `origRlimitNofile` in package syscall to hack.
-	syscallOrigRlimitNofile.Store(nil)
-}