fix: student category mapping from the program enrollment tool

[ruchamahabal]

Before:

Traceback (most recent call last):
  File "/home/frappe/frappe-bench/apps/frappe/frappe/app.py", line 68, in application
    response = frappe.api.handle()
  File "/home/frappe/frappe-bench/apps/frappe/frappe/api.py", line 55, in handle
    return frappe.handler.handle()
  File "/home/frappe/frappe-bench/apps/frappe/frappe/handler.py", line 31, in handle
    data = execute_cmd(cmd)
  File "/home/frappe/frappe-bench/apps/frappe/frappe/handler.py", line 67, in execute_cmd
    return frappe.call(method, **frappe.form_dict)
  File "/home/frappe/frappe-bench/apps/frappe/frappe/__init__.py", line 1172, in call
    return fn(*args, **newargs)
  File "/home/frappe/frappe-bench/apps/frappe/frappe/handler.py", line 234, in run_doc_method
    response = doc.run_method(method)
  File "/home/frappe/frappe-bench/apps/frappe/frappe/model/document.py", line 859, in run_method
    out = Document.hook(fn)(self, *args, **kwargs)
  File "/home/frappe/frappe-bench/apps/frappe/frappe/model/document.py", line 1148, in composer
    return composed(self, method, *args, **kwargs)
  File "/home/frappe/frappe-bench/apps/frappe/frappe/model/document.py", line 1131, in runner
    add_to_return_value(self, fn(self, *args, **kwargs))
  File "/home/frappe/frappe-bench/apps/frappe/frappe/model/document.py", line 853, in <lambda>
    fn = lambda self, *args, **kwargs: getattr(self, method)(*args, **kwargs)
  File "/home/frappe/frappe-bench/apps/erpnext/erpnext/education/doctype/program_enrollment_tool/program_enrollment_tool.py", line 62, in enroll_students
    prog_enrollment.student_category = stud.student_category
AttributeError: 'ProgramEnrollmentToolStudent' object has no attribute 'student_category'

After:

student-enrollment.mp4

[HoFaks]

we need this fix urgent .. many thanks