update min py version to 3.6

Author: TomDonoghue

README.rst

@@ -71,7 +71,7 @@ This documentation includes:
 Dependencies
 ------------
 
-FOOOF is written in Python, and requires Python >= 3.5 to run.
+FOOOF is written in Python, and requires Python >= 3.6 to run.
 
 It has the following required dependencies:
 

setup.py

@@ -20,7 +20,7 @@
     version = __version__,
     description = 'fitting oscillations & one-over f',
     long_description = long_description,
-    python_requires = '>=3.5',
+    python_requires = '>=3.6',
     author = 'The Voytek Lab',
     author_email = 'voyteklab@gmail.com',
     maintainer = 'Thomas Donoghue',
@@ -38,7 +38,6 @@
         'Operating System :: POSIX',
         'Operating System :: Unix',
         'Programming Language :: Python',
-        'Programming Language :: Python :: 3.5',
         'Programming Language :: Python :: 3.6',
         'Programming Language :: Python :: 3.7',
         'Programming Language :: Python :: 3.8',