Fix tests after py3.8 and 3.9 updates

[twisted-trac]

	@adiroiban reported
Trac ID	trac#10230
Type	release blocker: regression
Created	2021-07-15 10:12:44Z

This is the PR for fixing the tests.

https://bugs.python.org/issue44070

Observed on

3.9.6 - https://github.com/twisted/twisted/pull/1614/checks?check_run_id=3075151553#step:9:17972

3.8.11 - https://github.com/twisted/twisted/pull/1614/checks?check_run_id=3075151499#step:9:17972

If it takes more than 1 day to fix this, I plan to create a separate ticket with the scope of just skipping the failing tests and making trunk green again

and depending on the severity, update the release notes with information that latest 3.8 and 3.9 python versions are not supported.

Searchable metadata

trac-id__10230 10230
type__release_blocker__regression release blocker: regression
reporter__adiroiban adiroiban
priority__normal normal
milestone__None None
branch__ 
branch_author__ 
status__closed closed
resolution__fixed fixed
component__core core
keywords__None None
time__1626343964585254 1626343964585254
changetime__1626937683309895 1626937683309895
version__None None
owner__None None
cc__graingert

[twisted-trac]

	@graingert commented

#1628

[twisted-trac]

	@adiroiban commented

This was fixed in #1628

[twisted-trac]

	@glyph set status to closed

Please try to keep ticket state up to date