Stac-pydantic

- Move `validate_bbox` and `validate_datetime` field validation functions outside the Search class (to enable re-utilization)
- Remove `Search()._start_date` and ``Search()._end_date` private attributes
- Add `api.search.str_to_datetime(value: str) -> List[Optional[datetime.datetime]]` function

- Fix `Search` model to make sure `_start_date` and `_end_date` privateAttr are cleared on model initialization (72, sbrunato and vincentsarago)
- Fix bbox validation to allow anti-meridian crossing (167, ujjwal360)
- Add `octet_stream=application/octet-stream` to MimeTypes (169, tjellicoe-tpzuk)

- Fix URL comparison for Landing page conformance (163, gadomski)
- Fix `Search` validation when `datetime` is `None` (165, gadomski)

- Add optional `numberMatched` and `numberReturned` to `api.collections.Collections` model to match the OGC Common part2 specification

- Add more **MimeTypes** (geojsonseq, pbf, mvt, ndjson, openapi_yaml, pdf, csv, parquet)

- Cache remote JSON schemas for extensions (155, avbentem)
- add `requests` and `jsonschema` in a **validation** optional dependencies (156, vincentsarago)