Upgrade python version from 3.6 to 3.8

The newer versions of numpy and pandas have dropped support for
python version 3.6, and support only 3.8 at the minimum. The
Pipfile for this project already 3.8, this commit just updates the
setup.py to reflect this on pypi as well.

Signed-off-by: Karanraj Chauhan <[email protected]>

Author: chauhankaranraj

setup.py

@@ -39,7 +39,7 @@ def get_version():
     packages=setuptools.find_packages(),
     tests_require=["httmock"],
     classifiers=[
-        "Programming Language :: Python :: 3.6",
+        "Programming Language :: Python :: 3.8",
         "License :: OSI Approved :: MIT License",
         "Operating System :: OS Independent",
     ],