移除EPPlus 4.x版本不支持的LicenseContext代码

EPPlus 4.5.3.3版本不存在LicenseContext属性，该属性是5.0+版本新增的

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

WinFormsApp1/Form1.cs

@@ -101,9 +101,7 @@ namespace WinFormsApp1
             progressBar.Maximum = xlsxFiles.Length;
             progressBar.Value = 0;
 
-            // 设置EPPlus许可证上下文
-            OfficeOpenXml.ExcelPackage.LicenseContext = OfficeOpenXml.LicenseContext.NonCommercial;
-
+  
             var allData = new List<DataTable>();
             var headers = new List<string>();