Bump flask-migrate from 2.2.0 to 2.2.1 in /{{cookiecutter.app_name}}

Bumps [flask-migrate](https://github.com/miguelgrinberg/flask-migrate) from 2.2.0 to 2.2.1.
- [Release notes](https://github.com/miguelgrinberg/flask-migrate/releases)
- [Changelog](https://github.com/miguelgrinberg/Flask-Migrate/blob/master/CHANGELOG.md)
- [Commits](https://github.com/miguelgrinberg/flask-migrate/compare/v2.2.0...v2.2.1

)

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

{{cookiecutter.app_name}}/requirements/prod.txt

@@ -14,7 +14,7 @@ psycopg2==2.7.5
 SQLAlchemy==1.2.10
 
 # Migrations
-Flask-Migrate==2.2.0
+Flask-Migrate==2.2.1
 
 # Forms
 Flask-WTF==0.14.2