Add newly trained `calbert-tiny-uncased`
Calbert is an open-source ALBERT trained on the Catalan OSCAR dataset. This is the `tiny` version, newly trained from a completely rewrite [in this repo](https://github.com/codegram/calbert), now using SentencePiece which makes everything work much better with pipelines and the default tooling, as demonstrated in the model card.
# [Codecov](https://codecov.io/gh/huggingface/transformers/pull/5599?src=pr&el=h1) Report
> Merging [#5599](https://codecov.io/gh/huggingface/transformers/pull/5599?src=pr&el=desc) into [master](https://codecov.io/gh/huggingface/transformers/commit/f82a2a5e8e6827343322a4a9831924c5bb9bd2b2&el=desc) will **not change** coverage.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/huggingface/transformers/pull/5599/graphs/tree.svg?width=650&height=150&src=pr&token=9qOlN6Hb1c)](https://codecov.io/gh/huggingface/transformers/pull/5599?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master    #5599   +/-   ##
=======================================
  Coverage   76.69%   76.69%           
=======================================
  Files         145      145           
  Lines       25351    25351           
=======================================
  Hits        19444    19444           
  Misses       5907     5907           
```



------

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<|||||>looks great, thanks for sharing!