security_group.py: check cidr unstrictly to accept cidrs like 1.1.1.1/24 (#3701)

When I add a security group rule with cidr like 1.1.1.1/24, the rule is not applied on kvm hypervisor.
Ths issue does not exist in 4.13.0.0 and previous versions.

Author: ustcweizhou

scripts/vm/network/security_group.py

@@ -967,7 +967,7 @@ def parse_network_rules(rules):
         ipv6 = []
         for ip in cidrs.split(","):
             try:
-                network = ipaddress.ip_network(ip)
+                network = ipaddress.ip_network(ip, False)
                 if network.version == 4:
                     ipv4.append(ip)
                 else: