Update setup.py with long description and author email

The commit updates the setup.py file to include a long description of the package from README.md and adds an author email.

Author: DarkGL

setup.py

@@ -6,7 +6,10 @@
     name='simpay-api',
     version='3.0',
     description='Python wrapper for Simpay API',
-    author='Rafał Więcek <kontakt@simpay.pl>',
+    long_description=open('README.md').read(),
+    long_description_content_type="text/markdown",
+    author='Rafał Więcek',
+    author_email="kontakt@simpay.pl",
     url='https://github.com/SimPaypl/SimPay-API-Python',
     python_requires='>3.0',
     packages=find_packages(exclude=['tests*', 'examples*']),