Raise minimum Python version to 3.7

Author: mwilliamson

setup.py

@@ -20,18 +20,14 @@ def read(fname):
     packages=['precisely'],
     keywords="matcher matchers",
     install_requires=[],
-    python_requires='>=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*',
+    python_requires='>=3.7',
     license="BSD-2-Clause",
     classifiers=[
         'Development Status :: 5 - Production/Stable',
         'Intended Audience :: Developers',
         'License :: OSI Approved :: BSD License',
         'Programming Language :: Python',
-        'Programming Language :: Python :: 2',
-        'Programming Language :: Python :: 2.7',
         'Programming Language :: Python :: 3',
-        'Programming Language :: Python :: 3.5',
-        'Programming Language :: Python :: 3.6',
         'Programming Language :: Python :: 3.7',
         'Programming Language :: Python :: 3.8',
         'Programming Language :: Python :: 3.9',

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = py27,py35,py36,py37,py38,py39,pypy,docs
+envlist = py37,py38,py39,pypy,docs
 [testenv]
 changedir = {envtmpdir}
 deps=-r{toxinidir}/test-requirements.txt