Stac-pydantic

- Add id to landing page, making it a valid catalog (43, lossyrob)
- Make `item_assets` (item assets extension) a dictionary of assets (47, kylebarron)
- Add pre-commit to CI (48, kylebarron)
- Add a `Links` model with custom root type to represent a list of links (52)
- Move link related models to their own file (53)
- Add link factories for generating inferred links (55)
- Switch from relative to absolute imports (61)
- Serialize date type fields to `datetime.datetime` upon model creation (62)

- Remove enum restriction for asset roles (39).
- Remove enum restriction for band common name (40).

- Rename `proj` extension to `projection` (34).
- Remove `stac_extensions` enum requirement (35).

- Publish mypy type hints (30)
- Correct Cloud Optimized GeoTiff mime type (31)

- Add `created` and `updated` to stac common metadata, fix aliases. (28)

- Update to stac version 1.0.0-beta.2 (26)