Remove Python 3.5 support

setup.py

@@ -24,14 +24,12 @@ setup(
         'Intended Audience :: Developers',
         'License :: OSI Approved :: MIT License',
         'Programming Language :: Python :: 3',
-        'Programming Language :: Python :: 3.5',
         'Programming Language :: Python :: 3.6',
         'Programming Language :: Python :: 3.7',
         'Programming Language :: Python :: 3.8'
     ],
     keywords='ethereum',
-    # web3.py doesn't work on 3.5.2 and less (https://github.com/ethereum/web3.py/issues/1012)
-    python_requires='>=3.5.3,<4',
+    python_requires='>=3.6,<4',
     install_requires=[
         'web3==4.7.2',
         'eth-utils==1.10.0',

tox.ini

@@ -1,6 +1,6 @@
 [tox]
 envlist=
-    py{35,36,37,38}
+    py{36,37,38}
 
 [testenv]
 usedevelop=True
@@ -11,7 +11,6 @@ commands=
 deps=
     .[dev,streaming]
 basepython=
-    py35: python3.5
     py36: python3.6
     py37: python3.7
     py38: python3.8