Bump flask-cors from 3.0.8 to 3.0.9

Bumps [flask-cors](https://github.com/corydolphin/flask-cors) from 3.0.8 to 3.0.9.
- [Release notes](https://github.com/corydolphin/flask-cors/releases)
- [Changelog](https://github.com/corydolphin/flask-cors/blob/master/CHANGELOG.md)
- [Commits](corydolphin/flask-cors@3.0.8...3.0.9)

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

Author: dependabot-preview[bot]

requirements.txt

@@ -1,6 +1,6 @@
 beautifulsoup4==4.9.1
 elasticsearch==5.5.3
-flask-cors==3.0.8
+flask-cors==3.0.9
 gunicorn==19.10.0
 nested-lookup==0.2.21
 pylint==2.3.1