make error message when trying to quantize non floats more specific (#66050)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/66050
Adds the dtype to an error message when trying to quantize something
other than a float. This is useful for debugging quantization tools on
new models.
Test Plan:
```
x = torch.randn(1, 1, 1, 1, dtype=torch.double)
xq = torch.quantize_per_tensor(x, 0.01, 0, torch.quint8)
// error message now includes Double
```
Imported from OSS
Reviewed By: dagitses
Differential Revision: D31472849
fbshipit-source-id: 2331ffacefcbc6f8eca79694757d740de74a0f1d
