Bump flask-cors from 2.0.1 to 3.0.8

Bumps [flask-cors](https://github.com/corydolphin/flask-cors) from 2.0.1 to 3.0.8.
- [Release notes](https://github.com/corydolphin/flask-cors/releases)
- [Changelog](https://github.com/corydolphin/flask-cors/blob/master/CHANGELOG.md)
- [Commits](corydolphin/flask-cors@2.0.1...3.0.8)

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

requirements.txt

@@ -4,7 +4,7 @@ fakeredis==0.4.0
 Flask-Assets==2.0
 Flask-DebugToolbar==0.7.1
 Flask-SeaSurf==0.1.13
-Flask-Cors==2.0.1
+Flask-Cors==3.0.8
 Flask==0.11
 gevent==1.1.2
 gunicorn>=17.5,<=19.4.1