add_dll_directory only accepts absolute paths

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2020-12-01.10:03:32.145>
labels = ['3.9', 'docs']
title = 'add_dll_directory only accepts absolute paths'
updated_at = <Date 2020-12-01.10:03:32.145>
user = 'https://github.com/anntzer'

bugs.python.org fields:

activity = <Date 2020-12-01.10:03:32.145>
actor = 'Antony.Lee'
assignee = 'docs@python'
closed = False
closed_date = None
closer = None
components = ['Documentation']
creation = <Date 2020-12-01.10:03:32.145>
creator = 'Antony.Lee'
dependencies = []
files = []
hgrepos = []
issue_num = 42520
keywords = []
message_count = 1.0
messages = ['382228']
nosy_count = 2.0
nosy_names = ['docs@python', 'Antony.Lee']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = None
url = 'https://bugs.python.org/issue42520'
versions = ['Python 3.9']