[16.0 & 17.0] hr_expense_invoice error when expense report includes invoices from diferent providers

[TheCloneMaster]

Module

hr_expense_invoice

Describe the bug

If an expense report includes invoices from diferent providers, when posting move the report moves to "paid" and invoices are not reconciled as paid.

To Reproduce

Affected versions: 16.0 & 17.0

Steps to reproduce the behavior:

1. Create vendor bill for "provider 1"
2. Create vendor bill for "provider 2"
3. Create expense report, one line for bill created for provider 1 and another line for provider 2
4. Approve and post expense report
   As a result, the expense report is marked as paid, and the invoices remain open

Expected behavior
The Expense report should move to "register payment", and the original invoices should appear as "paid"

[TheCloneMaster]

The error is in _do_create_moves on hr_expense_sheet.py.
line 40 asks for the wrong vendor id...
== self.expense_line_ids.invoice_id.partner_id

it should be
== expense.invoice_id.partner_id

so that it takes the partner_id of current expense, not the one from the first expense from the report

I will upload a PR

Regards,
-Mario