improve unit tests for strings containing special characters

Co-authored-by: Moritz <mr-tz@users.noreply.github.com>

tests/test_rules.py

@@ -695,6 +695,7 @@ def test_string_values_special_characters():
     r = capa.rules.Rule.from_yaml(rule)
     children = list(r.statement.get_children())
     assert (String("hello\r\nworld") in children) == True
+    assert (String("bye\nbye") in children) == True
 
 
 def test_regex_values_always_string():