[Minor] using ls instead of find in workflow

Author: remyCases

.github/workflows/publish.yaml

@@ -112,7 +112,7 @@ jobs:
       # If some rules are not applicable, you can disable them
       # using the --excluded-rules or --excluded-rule-ids option
       - name: Validate package
-        run: meziantou.validate-nuget-package "$(find ${{ env.NuGetDirectory }} -type f "*.nupkg")" --excluded-rules AssembliesMustBeOptimized
+        run: meziantou.validate-nuget-package "$(ls ${{ env.NuGetDirectory }}/*.nupkg | head -1)" --excluded-rules AssembliesMustBeOptimized
 
   run_test:
     runs-on: ubuntu-latest