fix: expire_allocation api endpoint by fetching allocation object

[zeel-codder]

Add the code to fetch allocation in expire_allocation endpoint so that after code not break.

Traceback of error which is fixed

Traceback (most recent call last):
  File "apps/frappe/frappe/app.py", line 110, in application
    response = frappe.api.handle(request)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "apps/frappe/frappe/api/__init__.py", line 49, in handle
    data = endpoint(**arguments)
           ^^^^^^^^^^^^^^^^^^^^^
  File "apps/frappe/frappe/api/v1.py", line 36, in handle_rpc_call
    return frappe.handler.handle()
           ^^^^^^^^^^^^^^^^^^^^^^^
  File "apps/frappe/frappe/handler.py", line 49, in handle
    data = execute_cmd(cmd)
           ^^^^^^^^^^^^^^^^
  File "apps/frappe/frappe/handler.py", line 85, in execute_cmd
    return frappe.call(method, **frappe.form_dict)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "apps/frappe/frappe/__init__.py", line 1682, in call
    return fn(*args, **newargs)
           ^^^^^^^^^^^^^^^^^^^^
  File "apps/frappe/frappe/utils/typing_validations.py", line 31, in wrapper
    return func(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^
  File "apps/hrms/hrms/hr/doctype/leave_ledger_entry/leave_ledger_entry.py", line 193, in expire_allocation
    leaves = get_remaining_leaves(allocation)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "apps/hrms/hrms/hr/doctype/leave_ledger_entry/leave_ledger_entry.py", line 178, in get_remaining_leaves
    "employee": allocation.employee,
                ^^^^^^^^^^^^^^^^^^^
AttributeError: 'str' object has no attribute 'employee'

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 50.00000% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 72.80%. Comparing base (8f6e819) to head (5a1bcac).

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1576      +/-   ##
===========================================
- Coverage    72.85%   72.80%   -0.05%     
===========================================
  Files          202      202              
  Lines        11169    11173       +4     
===========================================
- Hits          8137     8135       -2     
- Misses        3032     3038       +6     

Files	Coverage Δ
...r/doctype/leave_ledger_entry/leave_ledger_entry.py	88.05% <50.00%> (-2.42%)	⬇️

... and 2 files with indirect coverage changes

[krantheman]

Can you add a test for this?

[zeel-codder]

Can you add a test for this?

Yes, will add.

[zeel-codder]

@krantheman I have added the test case.