Switch TLS tests to TLSv1.2+ only

This would more likely match a relevant production deployment.

Change-Id: I4ee2ff0c00a8e33fd069a782b32eed5fef62c01b
diff --git a/lib/tls b/lib/tls
index 0032449..6f2a65a 100644
--- a/lib/tls
+++ b/lib/tls
@@ -536,6 +536,7 @@
 <VirtualHost $f_host:$f_port>
     SSLEngine On
     SSLCertificateFile $DEVSTACK_CERT
+    SSLProtocol -all +TLSv1.3 +TLSv1.2
 
     # Disable KeepAlive to fix bug #1630664 a.k.a the
     # ('Connection aborted.', BadStatusLine("''",)) error