Stop support for Python 3.9 #2969

Job	Run time
build (ubuntu-latest, 3.10)	2m 58s
build (ubuntu-latest, 3.13)	3m 7s
build (windows-latest, 3.10)	7m 52s
link_check	3m 15s
check_release	1m 41s
Make SDist	20s
build (windows-latest, 3.13)	7m 35s
build (macos-latest, 3.10)	4m 51s
build (macos-latest, 3.13)	5m 10s
test_docs	46s
Test Lint	1m 7s
Test Minimum Versions	2m 22s
build (ubuntu-latest, pypy-3.10)	3m 46s
build (ubuntu-latest, 3.11)	2m 56s
Test Prereleases	2m 2s
test_without_debugpy (ubuntu-latest, 3.10)	1m 49s
build (ubuntu-latest, 3.12)	3m 3s
Install from SDist and Test	1m 56s
coverage	6s
tests_check	1s
	56m 43s

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