Fix create_server_certificate.sh

Docker image nginx:1.14.1 has no openssl installed. Therefore upgrading to nginx:1.19.10

test/certs/create_server_certificate.sh

@@ -24,7 +24,7 @@ fi
 # Create a nginx container (which conveniently provides the `openssl` command)
 ###############################################################################
 
-CONTAINER=$(docker run -d -v $DIR:/work -w /work -e SAN="$ALTERNATE_DOMAINS" nginx:1.14.1)
+CONTAINER=$(docker run -d -v $DIR:/work -w /work -e SAN="$ALTERNATE_DOMAINS" nginx:1.19.10)
 # Configure openssl
 docker exec $CONTAINER bash -c '
 	mkdir -p /ca/{certs,crl,private,newcerts} 2>/dev/null