[bug] allow tls 1.0 as a workaround for buster/sid

in systems with newer openssl, tls 1.0 has been disabled.
however, this breaks the ability of a client in a newer system to
connect with the openvpn servers on providers that are still on stretch.

platform needs to be upgraded.

-Related: #105

pkg/helper/args.go

@@ -23,6 +23,7 @@ var (
 		"--remote-cert-tls", "server",
 		"--dhcp-option", "DNS", nameserver,
 		"--log", LogFolder + "openvpn.log",
+		"--tls-version-min", "1.0",
 	}
 
 	allowendArgs = map[string][]string{