chaged to 3.7+ support in readme (ethereum#2428)

* chaged to 3.7+ support

* changed readme to 3.7.2+

* changed setup.py for python 3.7.2

Author: dbfreem

README.md

@@ -6,7 +6,7 @@
 
 A Python library for interacting with Ethereum, inspired by [web3.js](https://github.com/ethereum/web3.js).
 
-* Python 3.6+ support
+* Python 3.7.2+ support
 
 ---
 

setup.py

@@ -91,7 +91,7 @@
         "typing-extensions>=3.7.4.1,<5;python_version<'3.8'",
         "websockets>=10.0.0,<11",
     ],
-    python_requires='>=3.7,<3.11',
+    python_requires='>=3.7.2,<3.11',
     extras_require=extras_require,
     py_modules=['web3', 'ens', 'ethpm'],
     entry_points={"pytest11": ["pytest_ethereum = web3.tools.pytest_ethereum.plugins"]},