Fix formatting check in CI

.github/workflows/build-ilspy.yml

@@ -64,7 +64,7 @@ jobs:
         paths: "test-results/${{ matrix.configuration }}.xml"
 
     - name: Format check
-      run: dotnet format whitespace --verify-no-changes --verbosity detailed
+      run: dotnet format whitespace --verify-no-changes --verbosity detailed ILSpy.sln
       
     - name: Verify package contents
       if: matrix.configuration == 'debug'