Update Python version support. (#574)

This PR updates Python version classifiers to use the versions of Python currently supported by RAPIDS (3.8, 3.9).

Authors:
  - Bradley Dice (https://github.com/bdice)

Approvers:
  - H. Thomson Comer (https://github.com/thomcom)

URL: #574

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.black]
 line-length = 79
-target-version = ["py36"]
+target-version = ["py38"]
 include = '\.py?$'
 exclude = '''
 /(
@@ -16,4 +16,4 @@ exclude = '''
     build |
     dist
 )/
-'''
+'''

python/cuspatial/setup.py

@@ -20,8 +20,8 @@
         "Topic :: Scientific/Engineering",
         "License :: OSI Approved :: Apache Software License",
         "Programming Language :: Python",
-        "Programming Language :: Python :: 3.6",
-        "Programming Language :: Python :: 3.7",
+        "Programming Language :: Python :: 3.8",
+        "Programming Language :: Python :: 3.9",
     ],
     packages=find_packages(include=["cuspatial", "cuspatial.*"]),
     package_data={"cuspatial._lib": ["*.pxd"]},