Fix tensor label type inference in default collator
Quick fix to `default_data_collator` allowing it to recognize the correct type of PT tensor label inputs rather than always casting them to float (#5060)
What's the perf impact of a try/catch?<|||||># [Codecov](https://codecov.io/gh/huggingface/transformers/pull/5250?src=pr&el=h1) Report
> Merging [#5250](https://codecov.io/gh/huggingface/transformers/pull/5250?src=pr&el=desc) into [master](https://codecov.io/gh/huggingface/transformers/commit/49f6e7a3c6729025e0d412ee19786c71811a6390&el=desc) will **increase** coverage by `0.00%`.
> The diff coverage is `100.00%`.

[![Impacted file tree graph](https://codecov.io/gh/huggingface/transformers/pull/5250/graphs/tree.svg?width=650&height=150&src=pr&token=9qOlN6Hb1c)](https://codecov.io/gh/huggingface/transformers/pull/5250?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master    #5250   +/-   ##
=======================================
  Coverage   77.96%   77.96%           
=======================================
  Files         138      138           
  Lines       23886    23887    +1     
=======================================
+ Hits        18622    18623    +1     
  Misses       5264     5264           
```


| [Impacted Files](https://codecov.io/gh/huggingface/transformers/pull/5250?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [src/transformers/data/data\_collator.py](https://codecov.io/gh/huggingface/transformers/pull/5250/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9kYXRhL2RhdGFfY29sbGF0b3IucHk=) | `98.36% <100.00%> (+0.02%)` | :arrow_up: |
| [src/transformers/file\_utils.py](https://codecov.io/gh/huggingface/transformers/pull/5250/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9maWxlX3V0aWxzLnB5) | `76.42% <0.00%> (-0.39%)` | :arrow_down: |
| [src/transformers/modeling\_utils.py](https://codecov.io/gh/huggingface/transformers/pull/5250/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9tb2RlbGluZ191dGlscy5weQ==) | `91.26% <0.00%> (+0.12%)` | :arrow_up: |

------

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> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/huggingface/transformers/pull/5250?src=pr&el=footer). Last update [49f6e7a...513dcb5](https://codecov.io/gh/huggingface/transformers/pull/5250?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
<|||||>Is it supposed to be slower? I ran a quick profile iterating over IMDb train set and saw no difference, but can manually check for `torch.tensor` instead if that's preferred.