Bump pillow from 5.2.0 to 6.2.0 in /requirements

Bumps [pillow](https://github.com/python-pillow/Pillow) from 5.2.0 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@5.2.0...6.2.0)

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

requirements/requirements-base.txt

@@ -2,6 +2,6 @@ Kivy==1.11.1
 Kivy-Garden==0.1.4
 numpy==1.16.1
 opencv-python==4.1.1.26
-Pillow==5.2.0
+Pillow==6.2.0
 pyzbar==0.1.8
 xcamera==2019.928