fix: add missing id to check-dist compare step (#31) (#42)

The upload-artifact step's conditional referenced steps.diff.conclusion,
but the compare step had no id, so the reference was always undefined.
Add id: diff so the conditional resolves correctly.

Author: ifauzeee

.github/workflows/check-dist.yml

@@ -36,6 +36,7 @@ jobs:
         run: npm run build
 
       - name: Compare the expected and actual dist/ directories
+        id: diff
         run: |
           if [ "$(git diff --ignore-space-at-eol dist/ | wc -l)" -gt "0" ]; then
             echo "Detected uncommitted changes after build.  See status below:"