ENH: compress pdf files merging identical objects #5082

Job	Run time
pytest on windows	7m 4s
Check code style issues	42s
Build & verify package	11s
pytest on 3.8 (crypto-lib: cryptography)	5m 24s
pytest on 3.9 (crypto-lib: cryptography)	4m 53s
pytest on 3.10 (crypto-lib: cryptography)	5m 30s
pytest on 3.11 (crypto-lib: cryptography)	5m 13s
pytest on 3.12 (crypto-lib: cryptography)	6m 58s
pytest on 3.13-dev (crypto-lib: cryptography)	7m 7s
pytest on 3.8 (crypto-lib: pycryptodome)	5m 52s
pytest on 3.8 (crypto-lib: none)	4m 57s
Combine & check coverage.	16s
	54m 7s

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