Bump pillow from 6.2.2 to 8.1.1

Bumps [pillow](https://github.com/python-pillow/Pillow) from 6.2.2 to 8.1.1.
- [Release notes](https://github.com/python-pillow/Pillow/releases)
- [Changelog](https://github.com/python-pillow/Pillow/blob/master/CHANGES.rst)
- [Commits](python-pillow/Pillow@6.2.2...8.1.1)

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

requirements.txt

@@ -5,5 +5,5 @@ future==0.16.0
 configparser==3.5.0
 tabulate==0.7.7
 Pillow==6.2.2; python_version == '2.7'
-Pillow==8.0; python_version >= '3.6'
+Pillow==8.1.1; python_version >= '3.6'
 six==1.9