libct/sys/rlimit_linux: drop go:build tag

This is not needed since commit 16d73367 which sets 1.23 to be a
minimally required Go version.

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

libcontainer/system/rlimit_linux.go

@@ -1,5 +1,3 @@
-//go:build go1.23
-
 package system
 
 import (