CI: make sure build isn't broken by new examples

w-dream-html depends on external package dream-html, which, in turn,
depends on package dream, which makes it awkward to install dream-html
inside Dream's CI. So skip this example.

.github/workflows/test.yml

@@ -55,7 +55,7 @@ jobs:
       run: |
         set -e
         set -x
-        EXAMPLES=$(find example -maxdepth 1 -type d -not -name "w-mirage*" -not -name "r-tyxml" | grep -v "^example/0" | grep -v "^example$" | sort)
+        EXAMPLES=$(find example -maxdepth 1 -type d -not -name "w-mirage*" -not -name "r-tyxml" -not -name "w-dream-html" | grep -v "^example/0" | grep -v "^example$" | sort)
         shopt -s nullglob
         for EXAMPLE in $EXAMPLES
         do