[DataLoader] Follow-up Fix: TypeVars of Sampler (#100409)
API backward compatibility fixed:
https://github.com/pytorch/pytorch/pull/97338#discussion_r1169164163
Mapped Dataset can accept noninteger indices from custom Samplers.
Fixes #97338
Pull Request resolved: https://github.com/pytorch/pytorch/pull/100409
Approved by: https://github.com/ejguan, https://github.com/NivekT
