文件扩展名比较统一小写

performance/Performance.Services/ExtractExcelService/ExtractHelper/ExtractHelper.cs

@@ -196,7 +196,7 @@ public static bool IsXlsxFile(string filename)
                 int start = filename.LastIndexOf('.') + 1;
                 ext = filename.Substring(start, filename.Length - start);
             }
-            return ext == ExcelVersion.xlsx.ToString();
+            return ext.ToLower() == ExcelVersion.xlsx.ToString().ToLower();
         }
     }
 }