Fix error message when subclassing TypeVarTuple #2403

Job	Run time
Run tests (3.9.12)	17s
Run tests (3.10)	17s
Run tests (3.11)	13s
Run tests (3.11.0)	19s
Run tests (3.12)	21s
Run tests (3.9)	9s
Run tests (3.13)	18s
Run tests (3.10.4)	19s
Run tests (3.13.0)	20s
Run tests (3.12.0)	26s
Run tests (3.14)	25s
Run tests (pypy3.9)	21s
Run tests (pypy3.10)	29s
Run tests (pypy3.11)	25s
Create an issue if daily tests failed	0s
	4m 39s

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