Bump pillow from 5.4.1 to 6.2.0

Bumps [pillow](https://github.com/python-pillow/Pillow) from 5.4.1 to 6.2.0.
- [Release notes](https://github.com/python-pillow/Pillow/releases)
- [Changelog](https://github.com/python-pillow/Pillow/blob/master/CHANGES.rst)
- [Commits](python-pillow/Pillow@5.4.1...6.2.0)

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

requirements.txt

@@ -1,5 +1,5 @@
 numpy==1.16.2
-Pillow==5.4.1
+Pillow==6.2.0
 pyhocon==0.3.51
 pyparsing==2.3.1
 scikit-learn==0.20.3