Drf-extra-fields

- `psycopg` (psycopg 3) is now supported and it's used automatically instead of `psycopg2` if available.

- File objects without an actual file-system path can now be used in `Base64ImageField`, `Base64FileField` and `HybridImageField`

- File objects without an actual file-system path can now be used in `Base64ImageField`, `Base64FileField` and `HybridImageField`

- Development environment fixes & improvements.
- Since `Python 3.6` support is ended, the codebase is refactored/modernized for `Python 3.7`.
- `WebP` is added to default `ALLOWED_TYPES` of the `Base64ImageField`.
- Deprecated `imghdr` library is replaced with `filetype`.
- Unintended `Pillow` dependency is removed.

- :warning: **BACKWARD INCOMPATIBLE** :warning:
- Support for `Django 3.0` and `Django 3.1` is ended.
- `Django 4.0` is now supported.

- :warning: **BACKWARD INCOMPATIBLE** :warning:
- Support for `Python 3.6` is ended.