Fix error message when subclassing TypeVarTuple #2406

Job	Run time
Run tests (3.9)	13s
Run tests (3.10.4)	20s
Run tests (3.9.12)	19s
Run tests (3.11)	15s
Run tests (3.14)	25s
Run tests (3.13)	20s
Run tests (3.11.0)	21s
Run tests (3.10)	20s
Run tests (3.12.0)	25s
Run tests (3.12)	19s
Run tests (pypy3.9)	21s
Run tests (pypy3.10)	22s
Run tests (3.13.0)	24s
Run tests (pypy3.11)	24s
Create an issue if daily tests failed	0s
	4m 48s

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