Bump pillow from 7.1.0 to 8.1.1

Bumps [pillow](https://github.com/python-pillow/Pillow) from 7.1.0 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@7.1.0...8.1.1)

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

Author: dependabot[bot]

requirements.txt

@@ -17,7 +17,7 @@ docutils==0.15.2
 gunicorn==20.0.4
 idna==2.9
 jmespath==0.9.5
-Pillow==7.1.0
+Pillow==8.1.1
 psycopg2==2.7.3.2
 pycodestyle==2.5.0
 python-dateutil==2.8.1