Updated README, Dockerfile python version 3.11. (#539)

Author: Antoliny0919

Dockerfile

@@ -1,5 +1,5 @@
 # Pull base image
-FROM python:3.7.2
+FROM python:3.11
 
 # Set environment variables
 ENV PYTHONDONTWRITEBYTECODE 1

README.rst

@@ -45,7 +45,7 @@ Your environment variables are now set and you can proceed with the instructions
 Development Setup
 -----------------
 
-In a Python 3.7 virtual environment::
+In a Python 3.11 virtual environment::
 
     $ cd requirements
     $ pip install -r development.txt