[1.1] tests/int: add "requires systemd_vNNN"

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
(cherry picked from commit 58a811f6aa)
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

tests/integration/helpers.bash

@@ -441,6 +441,12 @@ function requires() {
 				skip_me=1
 			fi
 			;;
+		systemd_v*)
+			var=${var#systemd_v}
+			if [ "$(systemd_version)" -lt "$var" ]; then
+				skip "requires systemd >= v${var}"
+			fi
+			;;
 		no_systemd)
 			if [ -n "${RUNC_USE_SYSTEMD}" ]; then
 				skip_me=1