update setup to deprecate 3.6

doc/SETUP.org

@@ -42,7 +42,7 @@ You'd be really helping me, I want to make the setup as straightforward as possi
 * Few notes
 I understand that people who'd like to use this may not be super familiar with Python, pip or generally unix, so here are some useful notes:
 
-- only ~python >= 3.6~ is supported
+- only ~python >= 3.7~ is supported
 - I'm using ~pip3~ command, but on your system you might only have ~pip~.
 
   If your ~pip --version~ says python 3, feel free to use ~pip~.

setup.py

@@ -42,7 +42,7 @@ def main():
         author_email='karlicoss@gmail.com',
         description='A Python interface to my life',
 
-        python_requires='>=3.6',
+        python_requires='>=3.7',
         install_requires=INSTALL_REQUIRES,
         extras_require={
             'testing': [
@@ -60,10 +60,6 @@ def main():
                 'cachew>=0.8.0',
                 'mypy', # used for config checks
             ],
-            ':python_version<"3.7"': [
-                # used for some modules... hopefully reasonable to have it as a default
-                'dataclasses',
-            ],
         },
         entry_points={'console_scripts': ['hpi=my.core.__main__:main']},
     )