chore: simpler tox.ini, declare dev deps in pyproject.toml #1213

Job	Run time
Build test (3.10)	22s
Validate (3.10)	21s
Unit tests (3.8)	23s
Unit tests (3.9)	21s
Unit tests (3.10)	21s
Unit tests (3.11)	26s
Unit tests (3.12)	25s
Unit tests (3.13)	30s
Integration (3.10, 3.1/stable)	38m 16s
Quarantined Integration Tests (3.10, 3.1/stable)	33m 55s
Integration (3.10, 3.3/stable)	41m 27s
Quarantined Integration Tests (3.10, 3.3/stable)	34m 28s
Integration (3.10, 3.4/stable)	40m 55s
Quarantined Integration Tests (3.10, 3.4/stable)	41m 58s
Integration (3.10, 3.5/stable)	42m 19s
Quarantined Integration Tests (3.10, 3.5/stable)	43m 26s
	5h 19m 53s

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