BUG: Fix unpickling of string dtypes of legacy pandas versions #24232

Job	Run time
Pyodide build	2m 10s
Linux-32-bit	2m 0s
Linux-Musl	1m 57s
macos-14 actions-312.yaml	2m 11s
macos-13 actions-312.yaml	1m 58s
macos-14 actions-313.yaml	2m 14s
macos-14 actions-311.yaml	2m 12s
windows-latest actions-311.yaml	2m 0s
macos-13 actions-311.yaml	2m 12s
windows-latest actions-312.yaml	2m 1s
windows-latest actions-313.yaml	2m 1s
windows-latest actions-310.yaml	2m 0s
macos-14 actions-310.yaml	1m 59s
python-dev	0s
macos-13 actions-310.yaml	1m 59s
macos-13 actions-313.yaml	2m 4s
ubuntu-24.04-arm actions-312.yaml	2m 41s
ubuntu-24.04-arm actions-310.yaml	2m 5s
Pyarrow Nightly	2m 13s
ubuntu-24.04 actions-310.yaml	2m 11s
Freethreading	2m 13s
ubuntu-24.04 actions-312.yaml	2m 12s
Locale: zh_CN	2m 13s
ubuntu-24.04 actions-311.yaml	2m 14s
Numpy Dev	2m 11s
Minimum Versions	2m 13s
Future infer strings	2m 12s
ubuntu-24.04-arm actions-313.yaml	2m 33s
Pypy	1m 20s
ubuntu-24.04-arm actions-311.yaml	2m 33s
Locale: it_IT	2m 12s
Future infer strings (without pyarrow)	2m 14s
ubuntu-24.04 actions-313.yaml	2m 12s
Downstream Compat	2m 11s
	1h 10m 51s

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