remove Python 3.6 setup & envs

Author: jGaboardi

.github/workflows/build_docs.yml

@@ -20,7 +20,7 @@
      strategy:
        matrix:
          os: ['ubuntu-latest']
-         environment-file: [ci/38.yaml]
+         environment-file: [ci/39.yaml]
          experimental: [false]
      defaults:
        run:

ci/36.yaml

@@ -87,7 +87,6 @@ def setup_package():
             "Topic :: Scientific/Engineering :: GIS",
             "License :: OSI Approved :: BSD License",
             "Programming Language :: Python",
-            "Programming Language :: Python :: 3.6",
             "Programming Language :: Python :: 3.7",
             "Programming Language :: Python :: 3.8",
             "Programming Language :: Python :: 3.9",
@@ -96,7 +95,7 @@ def setup_package():
         install_requires=install_reqs,
         extras_require=extras_reqs,
         cmdclass={"build_py": build_py},
-        python_requires=">3.5",
+        python_requires=">=3.7",
     )