Bump pillow from 6.1.0 to 6.2.1

Bumps [pillow](https://github.com/python-pillow/Pillow) from 6.1.0 to 6.2.1.
- [Release notes](https://github.com/python-pillow/Pillow/releases)
- [Changelog](https://github.com/python-pillow/Pillow/blob/master/CHANGES.rst)
- [Commits](python-pillow/Pillow@6.1.0...6.2.1)

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

requirements.txt

@@ -28,7 +28,7 @@ lxml==4.4.1
 oauthlib==3.1.0
 # olefile==0.46
 # pandas==0.23.4
-Pillow==6.1.0
+Pillow==6.2.1
 psycopg2-binary==2.8.3
 pyIsEmail==1.3.2
 # pyOpenSSL==18.0.0