ci: fix wrong path for wix being set

Author: pietroalbini

src/ci/scripts/install-wix.sh

@@ -8,10 +8,10 @@ IFS=$'\n\t'
 source "$(cd "$(dirname "$0")" && pwd)/../shared.sh"
 
 if isWindows; then
+    ciCommandSetEnv WIX "$(pwd)/wix"
+
     curl -O "${MIRRORS_BASE}/wix311-binaries.zip"
     mkdir -p wix/bin
     cd wix/bin
     7z x ../../wix311-binaries.zip
-
-    ciCommandSetEnv WIX "$(pwd)/wix"
 fi