Add `attrs.validators.or_` validator #1007

Job	Run time
Check types using pyright	16s
Run CodSpeed benchmarks	2m 1s
Verify dev env (ubuntu-latest)	28s
Build docs & run doctests	20s
Verify dev env (windows-latest)	49s
Tests & Mypy on 3.7	50s
Tests & Mypy on 3.8	33s
Tests & Mypy on 3.9	53s
Tests & Mypy on 3.10	59s
Tests & Mypy on 3.11	48s
Tests & Mypy on 3.12	1m 10s
Tests & Mypy on 3.13	46s
Tests & Mypy on pypy-3.8	51s
Tests & Mypy on pypy-3.9	47s
Tests & Mypy on pypy-3.10	38s
Combine & check coverage.	8s
required-checks-pass	2s
	12m 19s

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