use ConvertedType instead of Type to determine if param array has been passed

src/Analyzers/Core/Analyzers/ValidateFormatString/AbstractValidateFormatStringDiagnosticAnalyzer.cs

@@ -204,7 +204,7 @@ private static bool IsValidFormatMethod(ISyntaxFacts syntaxFacts, SyntaxNode exp
             }
 
             var expression = syntaxFacts.GetExpressionOfArgument(argsArgument);
-            return semanticModel.GetTypeInfo(expression).Type;
+            return semanticModel.GetTypeInfo(expression).ConvertedType;
         }
 
         protected SyntaxNode? TryGetArgument(