Need to upgrade the version of SQLAlchemy

[Deborah-Digges]

Issue Summary

The current version of SQLAlchemy does not work with the latest version of MySQL and needs to be upgraded.

This is because the latest version of MySQL (8.x) has deprecated tx_isolation. More details here: https://stackoverflow.com/questions/50156520/cannot-connect-to-a-local-mysql-db-with-sqlalchemy-on-windows-machine

Steps to Reproduce

1. Start the app using python app.py
2. You will see the following stack trace:

  File "/Users/username/github/open-source-library-data-collector/venv/lib/python3.6/site-packages/pymysql/err.py", line 107, in raise_mysql_exception
    raise errorclass(errno, errval)
sqlalchemy.exc.InternalError: (pymysql.err.InternalError) (1193, "Unknown system variable 'tx_isolation'")

Technical details:

• Python Version: 3.2.6
• Browser/OS: Chrome/MacOS
• Database/Version: Ver 8.0.12 for macos10.13 on x86_64 (MySQL Community Server - GPL)