Drop requirements.txt file and move dependencies to pyproject.toml

[giohappy]

The requirements.txt file is not required, since dependencies are installed when installing the Geonode package with pip install. Removing the file also solves the problem of having to keep two lists of dependencies in sync, which is a manual process.
We will also move the setup configurations to pyproject.toml and drop the setup.cfg file

[cesarbenjamindotnet]

finally