Close the temp ttyout file in the SGR deduplication test

The file is opened under t.TempDir() and never closed, so the cleanup
that TempDir registers cannot remove it on Windows, where an open file
cannot be unlinked. The test itself passes; it is the cleanup that fails
the run. history_test.go and options_test.go already close theirs.

src/tui/light_test.go

@@ -434,6 +434,7 @@ func TestLightRendererSGRDeduplication(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
+	defer out.Close()
 	r.ttyout = out
 
 	w := r.NewWindow(0, 0, 40, 4, WindowList, MakeBorderStyle(BorderNone, true), false).(*LightWindow)