Bump pillow from 3.1.1 to 6.2.2

Bumps [pillow](https://github.com/python-pillow/Pillow) from 3.1.1 to 6.2.2.
- [Release notes](https://github.com/python-pillow/Pillow/releases)
- [Changelog](https://github.com/python-pillow/Pillow/blob/master/CHANGES.rst)
- [Commits](python-pillow/Pillow@3.1.1...6.2.2)

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

Author: dependabot[bot]

requirements.txt

@@ -30,7 +30,7 @@ django-widgeter==0.1
 feedparser==5.1.3
 django-mptt==0.7.4
 requests==2.20.0
-pillow==3.1.1
+pillow==6.2.2
 paramiko==1.17.6
 urllib3==1.14
 ecdsa==0.13.3