Fix off by one in pickle protocol tests #2085

Job	Run time
Run tests (3.9)	7s
Lint	9s
Run tests (3.9.12)	15s
Run tests (3.10)	7s
Run tests (3.10.4)	13s
Run tests (3.11)	7s
Run tests (3.11.0)	16s
Run tests (3.12)	8s
Run tests (3.12.0)	17s
Run tests (3.13)	7s
Run tests (3.13.0)	12s
Run tests (3.14)	14s
Run tests (pypy3.9)	7s
Run tests (pypy3.10)	14s
Create an issue if daily tests failed	0s
	2m 33s

Provide feedback