travis: update the ngtcp2 build to use the latest OpenSSL patch

... which also makes it OpenSSL 1.1.1d based and not v3.
diff --git a/scripts/travis/before_script.sh b/scripts/travis/before_script.sh
index 3baa86c..32fc4b4 100755
--- a/scripts/travis/before_script.sh
+++ b/scripts/travis/before_script.sh
@@ -26,7 +26,7 @@
 
 if [ "$NGTCP2" = yes ]; then
   cd $HOME
-  git clone --depth 1 -b openssl-quic-draft-23 https://github.com/tatsuhiro-t/openssl possl
+  git clone --depth 1 -b OpenSSL_1_1_1d-quic-draft-27 https://github.com/tatsuhiro-t/openssl possl
   cd possl
   ./config enable-tls1_3 --prefix=$HOME/ngbuild
   make