Import error on colab with version 1.5.1

I get the following error when simply installing and importing dataclass_array on a colab.

```
!pip install dataclass-array

import dataclass_array as dca
```

raises:

```
[/usr/local/lib/python3.10/dist-packages/dataclass_array/array_dataclass.py](https://localhost:8080/#) in DataclassArray()
582 # ====== Internal ======
583
--> 584 @epy.cached_property
585 def _all_fields_empty(self) -> bool:
586 """Returns True if the `dataclass_array` is invalid."""

AttributeError: module 'etils.epy' has no attribute 'cached_property'
```

Not sure what I am missing. Any help would be great. Thanks in advance!