Bump sqlalchemy from 1.2.5 to 1.3.0 in /FlaskPythonHerokuDB

Bumps [sqlalchemy](https://github.com/sqlalchemy/sqlalchemy) from 1.2.5 to 1.3.0.
- [Release notes](https://github.com/sqlalchemy/sqlalchemy/releases)
- [Changelog](https://github.com/sqlalchemy/sqlalchemy/blob/master/CHANGES)
- [Commits](https://github.com/sqlalchemy/sqlalchemy/commits)

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

FlaskPythonHerokuDB/requirements.txt

@@ -13,6 +13,6 @@ marshmallow-sqlalchemy==0.13.2
 psycopg2-binary==2.8.6
 pytz==2018.3
 six==1.11.0
-SQLAlchemy==1.2.5
+SQLAlchemy==1.3.0
 Werkzeug==0.15.5