Update histogram method in map preview

here we may want to update this in the future (when we update titiler version) to

```python

data = ImageData(src_dst.input.values, mask=boolean_mask)
return data.statistics(
categorical=True,
hist_options={"bins": 10},
)
```

_Originally posted by @vincentsarago in https://github.com/developmentseed/titiler-xarray/pull/26#discussion_r1329309553_