Remove python 3.8 compatibility cruft #1668

Job	Run time
old-dependencies	41s
lint	46s
test (windows-latest, 3.13.0, --cov-fail-under=100)	2m 27s
test (macos-latest, 3.13.0, --cov-fail-under=100)	1m 56s
test (ubuntu-latest, 3.13.0, --cov-fail-under=100)	1m 46s
test (ubuntu-latest, 3.12.4)	2m 37s
test (ubuntu-latest, 3.11.5)	2m 6s
test (ubuntu-latest, 3.10.13)	2m 27s
test (ubuntu-latest, 3.9.18)	2m 8s
build / build	19s
attest	0s
check / check	2s
deploy	0s
	17m 15s

Provide feedback