bump: min Python 3.9 #1001

Job	Run time
check-precommit / pre-commit	10s
check-docs / make-docs (html)	2m 23s
check-md-links-default / markdown-link-check	11s
check-docs / make-docs (doctest)	2m 19s
check-schema-fixed / schema	16s
check-docs / make-docs (linkcheck)	2m 21s
check-schema-latest / schema	16s
check-typing / mypy	17s
check-md-links-w-config / markdown-link-check	12s
check-package / init-store	6s
check-package-extras / init-store	2s
check-package-extras / pkg-build (ubuntu-latest)	17s
check-package / pkg-build (ubuntu-22.04, 3.10)	20s
check-schema	1s
check-package-extras / pkg-check (ubuntu-22.04, 3.10)	17s
check-package-extras / pkg-check (macos-13, 3.10)	37s
check-package-extras / pkg-check (windows-2022, 3.10)	1m 4s
check-package / pkg-check (ubuntu-22.04, 3.9)	19s
check-package / pkg-check (ubuntu-22.04, 3.12)	14s
check-package / pkg-check (macos-13, 3.9)	23s
check-package / pkg-check (macos-13, 3.12)	24s
check-package / pkg-check (windows-2022, 3.9)	55s
check-package / pkg-check (windows-2022, 3.12)	43s
check-package-extras / pkg-guardian	1s
check-package / pkg-guardian	1s
	14m 9s

Provide feedback