BUG: Improve PdfWriter handing of context manager #5515

Job	Run time
Build & verify package	14s
pytest on 3.8 (crypto-lib: cryptography)	5m 22s
Check code style issues	31s
pytest on 3.9 (crypto-lib: cryptography)	5m 33s
pytest on windows	6m 48s
pytest on 3.10 (crypto-lib: cryptography)	5m 27s
pytest on 3.11 (crypto-lib: cryptography)	5m 39s
pytest on 3.12 (crypto-lib: cryptography)	7m 12s
pytest on 3.13 (crypto-lib: cryptography)	7m 11s
pytest on 3.8 (crypto-lib: pycryptodome)	5m 11s
pytest on 3.8 (crypto-lib: none)	5m 19s
Combine & check coverage.	20s
	54m 47s

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