Close encrypted filestream

[ZakkyR]

An error "Error saving file {file path}" occurred when saving an encrypted file.

using (ExcelPackage pck = new ExcelPackage(new FileInfo("path/to/encrypted/file.xlsx"), true, "password"))            
 {
    // Excel operation processing

    pck.Save(); // Error saving file path/to/encrypted/file.xlsx
 }

The process was locked because there was a file stream that was not closed.
The error disappeared when I corrected it.

You can test with "EPPlusTest.Encrypt.ReadWriteEncrypt()".

I am glad if you merge because it is necessary for business.