Merge pull request #122 from ocefpaf/drop_py36

drop py36

Author: ocefpaf

setup.py

@@ -53,7 +53,6 @@ def walk_subpkg(name):
     keywords="data visualization",
     classifiers=[
         "Programming Language :: Python :: 3",
-        "Programming Language :: Python :: 3.6",
         "Programming Language :: Python :: 3.7",
         "Programming Language :: Python :: 3.8",
         "Programming Language :: Python :: 3.9",
@@ -73,6 +72,6 @@ def walk_subpkg(name):
     tests_require=["pytest"],
     license=LICENSE,
     install_requires=install_requires,
-    python_requires=">=3.5",
+    python_requires=">=3.7",
     zip_safe=False,
 )