Preserve AttributeError in slotted classes with cached_property #920

Job	Run time
Check types using pyright	15s
Verify dev env (ubuntu-latest)	28s
Build docs & run doctests	16s
Verify dev env (windows-latest)	41s
Tests & Mypy on 3.7	49s
Tests & Mypy on 3.8	53s
Tests & Mypy on 3.9	46s
Tests & Mypy on 3.10	57s
Tests & Mypy on 3.11	47s
Tests & Mypy on 3.12	1m 9s
Tests & Mypy on 3.13	1m 51s
Tests & Mypy on pypy-3.8	41s
Tests & Mypy on pypy-3.9	53s
Tests & Mypy on pypy-3.10	48s
Combine & check coverage.	13s
required-checks-pass	2s
	11m 29s

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