bpo-33570: TLS 1.3 ciphers for OpenSSL 1.1.1 (GH-6976)

Change TLS 1.3 cipher suite settings for compatibility with OpenSSL
1.1.1-pre6 and newer. OpenSSL 1.1.1 will have TLS 1.3 cipers enabled by
default.

Also update multissltests and Travis config to test with latest OpenSSL.

Signed-off-by: Christian Heimes <christian@python.org>
diff --git a/Tools/ssl/multissltests.py b/Tools/ssl/multissltests.py
index 2efc425..bbc5c66 100755
--- a/Tools/ssl/multissltests.py
+++ b/Tools/ssl/multissltests.py
@@ -45,16 +45,16 @@
 ]
 
 OPENSSL_RECENT_VERSIONS = [
-    "1.0.2n",
-    "1.1.0g",
-    "1.1.1-pre1",
+    "1.0.2o",
+    "1.1.0h",
+    "1.1.1-pre6",
 ]
 
 LIBRESSL_OLD_VERSIONS = [
 ]
 
 LIBRESSL_RECENT_VERSIONS = [
-    "2.7.1",
+    "2.7.3",
 ]
 
 # store files in ../multissl