Bump pillow from 4.1.1 to 7.1.0 (#1218)

Bumps [pillow](https://github.com/python-pillow/Pillow) from 4.1.1 to 7.1.0.
- [Release notes](https://github.com/python-pillow/Pillow/releases)
- [Changelog](https://github.com/python-pillow/Pillow/blob/master/CHANGES.rst)
- [Commits](python-pillow/Pillow@4.1.1...7.1.0)

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

requirements.txt

@@ -27,5 +27,5 @@ pandas
 scikit-image
 # pillow >= 4.2 will throw error when trying to write mode RGBA as JPEG,
 # this is a workaround to the issue.
-pillow==4.1.1
+pillow==7.1.0
 wget