BUG: encode_pdfdocencoding() always returns bytes #4321

Job	Run time
Build & verify package	13s
pytest on windows	4m 47s
Check code style issues	35s
pytest on 3.7 (crypto-lib: cryptography)	3m 25s
pytest on 3.8 (crypto-lib: cryptography)	3m 39s
pytest on 3.9 (crypto-lib: cryptography)	3m 44s
pytest on 3.10 (crypto-lib: cryptography)	3m 33s
pytest on 3.11 (crypto-lib: cryptography)	3m 26s
pytest on 3.12 (crypto-lib: cryptography)	5m 22s
pytest on 3.7 (crypto-lib: pycryptodome)	3m 27s
pytest on 3.7 (crypto-lib: none)	3m 20s
Combine & check coverage.	17s
	35m 48s

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