Update Simpay API version to 3.0.1

The Simpay API version has been updated from 3.0 to 3.0.1 in the setup.py file, which is a Python wrapper for the Simpay API. The long description of the package is now read from README.md and its content type is set as text/markdown.

Additional headers with informations

Fix generate signature parameters

2.0 Release

Update