STY: Use hasattr to determine if an object has an attribute #4918

Job	Run time
pytest on windows	6m 31s
Check code style issues	49s
Build & verify package	14s
pytest on 3.7 (crypto-lib: cryptography)	4m 52s
pytest on 3.8 (crypto-lib: cryptography)	5m 0s
pytest on 3.9 (crypto-lib: cryptography)	4m 59s
pytest on 3.10 (crypto-lib: cryptography)	4m 59s
pytest on 3.11 (crypto-lib: cryptography)	4m 43s
pytest on 3.12 (crypto-lib: cryptography)	4m 59s
pytest on 3.7 (crypto-lib: pycryptodome)	4m 59s
pytest on 3.7 (crypto-lib: none)	4m 58s
Combine & check coverage.	0s
	47m 3s

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