General: Fix last version function

[iLLiCiTiT]

Brief description

Function get_last_verisons does not crash if fields are passed and do not contain "parent" key.

Description

Missing "parent" key was not added to required fields properly.

Testing notes:

Bug was spotted in standalone publisher where in specific cases is called this function.

It is possible to test in Tray > Admin > Console

from openpype.client import get_last_versions, get_subsets

# Fill your project name
project_name = "some project name"

# Find any random subset
any_subset = None
for subset in get_subsets(project_name):
    any_subset = subset
    break

# Run fixed function with fields that don't have "parent" key
# - this line should not crash
versions = get_last_versions(project_name, [any_subset["_id"]], fields=["name"])