test/tools: fix shell confirm format test syntax

tests/test_tools/test_danger.py

@@ -114,10 +114,9 @@ async def test_confirm_deny_with_comment() -> None:
     assert "user comment:" in out
     assert "too destructive" in out
 
+
 def test_shell_confirm_formats_command_placeholder() -> None:
-    script = "line1" + "
-" + "line2" + "
-" + "line3"
+    script = chr(10).join(["line1", "line2", "line3"])
     reason = classify_danger(
         "run_command",
         {"command": ["bash", "-c", script]},