fix: fix 'consider-using-set-comprehension' for pylint

.pylintrc

@@ -8,6 +8,7 @@ enable=anomalous-backslash-in-string,
         bare-except,
         broad-exception-caught,
         consider-using-f-string,
+        consider-using-set-comprehension,
         cyclic-import,
         dangerous-default-value,
         disallowed-name,

src/wuttjamaican/problems.py

@@ -200,7 +200,7 @@ class ProblemHandler(GenericHandler):
         :returns: List of system keys.
         """
         checks = self.get_all_problem_checks()
-        return sorted(set([check.system_key for check in checks]))
+        return sorted({check.system_key for check in checks})
 
     def get_system_title(self, system_key):
         """