Only allow Python > 3.7 (#23)

Author: fabaff

setup.py

@@ -28,6 +28,7 @@
     install_requires=["aiohttp<4", "defusedxml", "attrs"],
     packages=["connect_box"],
     zip_safe=True,
+    python_requires=">=3.7",
     classifiers=[
         "Development Status :: 3 - Alpha",
         "Environment :: Console",
@@ -36,8 +37,8 @@
         "Operating System :: MacOS :: MacOS X",
         "Operating System :: Microsoft :: Windows",
         "Operating System :: POSIX",
-        "Programming Language :: Python :: 3.6",
-        "Programming Language :: Python :: 3.7",
+        "Programming Language :: Python :: 3.8",
+        "Programming Language :: Python :: 3.9",
         "Topic :: Utilities",
     ],
 )