MNT: require py39, enable pyupgrade for ruff, upgrade lang features #985

Job	Run time
Linting (Ruff)	55s
Linting (Ruff)	55s
Test import order (isort)	39s
Test import order (isort)	39s
Test readme renders on PyPi	18s
Test readme renders on PyPi	18s
Tests on 3.9 (Minimum Versions)	16m 20s
Tests on 3.9 (Minimum Versions)	14m 3s
Tests on 3.9	14m 22s
Tests on 3.9	14m 22s
Tests on 3.10	14m 42s
Tests on 3.10	14m 42s
Tests on 3.11	13m 44s
Tests on 3.11	13m 44s
Tests on 3.12	18m 26s
Tests on 3.12	18m 26s
Test Docs / Build Documentation	5m 17s
Test Docs / Build Documentation	5m 17s
	2h 47m 9s

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