Add ShahadataPresidentRaeesi To Holidays

[qasimsina]

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[what-the-diff]

PR Summary

• Addition of a new constant variable
  A new constant variable called ShahadataPresidentRaeesi has been introduced in the IranHolidays.cs file.

• Creation of a New IranHoliday Object
  A new IranHoliday object has been created. This object utilizes the newly added constant ShahadataPresidentRaeesi in its description.

Note: Some necessary adjustments have been made to improve the formatting of the diff.