CI: fix error in download-artifact action

The download-artifact action tries to download all artifacts, but fails
if an artifact is not in zip format. At some point something decided to
start uploading Docker build summary, which is not in zip format,
causing this problem.

[Insert rant about Github Actions here]

actions/toolkit#1874 (review)

Author: stintel

.github/workflows/build-willow.yml

@@ -107,6 +107,8 @@ jobs:
     steps:
       - name: download artifacts
         uses: actions/download-artifact@v4
+        with:
+          pattern: '!*.dockerbuild'
 
       - name: pwd
         run: pwd