Fix regex patterns (#2442)

slither/solc_parsing/expressions/expression_parsing.py

@@ -501,7 +501,9 @@ def parse_expression(expression: Dict, caller_context: CallerContextExpression)
                 referenced_declaration = expression["attributes"]["referencedDeclaration"]
 
         if t:
-            found = re.findall(r"[struct|enum|function|modifier] \(([\[\] ()a-zA-Z0-9\.,_]*)\)", t)
+            found = re.findall(
+                r"(?:struct|enum|function|modifier) \(([\[\] ()a-zA-Z0-9\.,_]*)\)", t
+            )
             assert len(found) <= 1
             if found:
                 value = value + "(" + found[0] + ")"