Tighten the assertion

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

Author: JokeWaumans

tests/test_formatting.py

@@ -312,7 +312,7 @@ def test_stylechecker_valid_rst():
         checker.run()
 
         # Should not find any issues
-        assert not checker.issues_found or not checker.lint_issues_found
+        assert not checker.issues_found and not checker.lint_issues_found
 
 
 def test_stylecheck_with_custom_line_length():