enable the filter extension for collection_items endpoint

[vincentsarago]

https://github.com/stac-utils/stac-fastapi-pgstac/blob/9a3797a149f17491735a6134109363f681d934c5/stac_fastapi/pgstac/app.py#L61C1-L70

ref stac-utils/stac-fastapi#756

[drnextgis]

@vincentsarago to avoid overlapping efforts, I’d like to know if you’re planning to address this issue?

[vincentsarago]

I'm not planning it right now but I know we have similar things to fix in upcoming PR so I guess we can take the responsibility to do it @drnextgis

[drnextgis]

Thank you!