Bump sqlalchemy from 1.3.7 to 1.3.8 in /{{cookiecutter.app_name}} (#543)

Bumps [sqlalchemy](https://github.com/sqlalchemy/sqlalchemy) from 1.3.7 to 1.3.8.
- [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-preview[bot] <support@dependabot.com>