Fix error message when subclassing TypeVarTuple #2755

Job	Run time
Run tests (3.12)	12s
Run tests (pypy3.9)	21s
Run tests (3.13)	15s
Run tests (3.14)	16s
Run tests (3.13.0)	22s
Run tests (3.9)	23s
Run tests (pypy3.11)	22s
Run tests (pypy3.10)	23s
Run tests (3.12.0)	22s
Run tests (3.9.12)	25s
Run tests (3.11)	16s
Run tests (3.10)	14s
Run tests (3.11.0)	23s
Run tests (3.10.4)	23s
Create an issue if daily tests failed	0s
	4m 37s

Provide feedback