CI: vtest: temporarily build from the sd-notify PR

Build VTest temporarily from the sd-notify PR until the
https://github.com/vtest/VTest/pull/41 is merged.

This PR allows starting with -Ws in order to have more reliables tests
in master-worker mode.

scripts/build-vtest.sh

@@ -2,7 +2,7 @@
 
 set -eux
 
-curl -fsSL https://github.com/vtest/VTest/archive/master.tar.gz -o VTest.tar.gz
+curl -fsSL https://github.com/wlallemand/VTest/archive/refs/heads/haproxy-sd_notify.tar.gz -o VTest.tar.gz
 mkdir ../vtest
 tar xvf VTest.tar.gz -C ../vtest --strip-components=1
 # Special flags due to: https://github.com/vtest/VTest/issues/12