Httpie-edgegrid

FEATURES/ENHANCEMENTS:

* Discontinued support for Python <= 3.8; Python 3.9 is now the minimum supported version.
* Updated several dependencies in `setup.py`.
* Started generating the `requirements.txt` and `dev-requirements.txt` files using `pip-compile`,
so that they contain the full set of project dependencies.

BUG FIXES:

* Fixed installation failure with HTTPie CLI ([I76](https://github.com/akamai/httpie-edgegrid/issues/76)).

FEATURES/ENHANCEMENTS:

* Updated the `pyOpenSSL`, `pylint`, and test dependencies.

FEATURES/ENHANCEMENTS:

* Updated the `urllib3` and test dependencies.

FEATURES/ENHANCEMENTS:

* Updated the `httpie` and `pyOpenSSL` dependencies.

BUG FIXES:

* Fixed a bug related to returning an unexpected error when performing a basic API call ([I34](https://github.com/akamai/httpie-edgegrid/issues/34)).

FEATURES/ENHANCEMENTS:

* Updated the `edgegrid-python` dependency.

FEATURES/ENHANCEMENTS:

* Updated the `edgegrid-python` dependency.