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

@@ -10,6 +10,6 @@ Cython==0.29.2
 dsntnn==0.4.0a0
 imgaug==0.2.7
 matplotlib==3.0.2
-Pillow==5.4.1
+Pillow==6.2.0
 scripts==2.0
 skimage