Fpds

- Enables the `fpdsRequest` class to be callable (this was functionality that was enabled in v1.0.0, but was removed in v1.3.0 by accident). Prevents the `fpds parse` command from failing

Thanks to vdavez for the catch!

- Makes async API calls using `asyncio`/`aiohttp` structure, thus removing dependency on external `requests` library
- Fixes additional type issues within core library
- Restructures `utilities/params.py` and its references in the CLI
- Adds support for FPDS ATOM feed `v1.5.3` (i.e. all advanced filters supported in `fpds.gov` are supported with this library)
- Moves PyPI packaging to `pyproject.toml`

Addresses a bug where requests with less than 20 records were being truncated since the last ATOM feed request was being truncated at 10 records.

- Includes `award_type` field to delineate an award as either `AWARD` or an `IDV`.
- Provides a more explicit key name convetion for JSON data to prevent overwriting of duplicate fields (i.e. `PIID`). This was observed in cases when an award has a referenced IDV value.
- More object-oriented programming by creating child classes to better represent XML objects.