Bump pillow from 3.0.0 to 8.1.1

Bumps [pillow](https://github.com/python-pillow/Pillow) from 3.0.0 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@3.0.0...8.1.1)

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

requirements.txt

@@ -24,7 +24,7 @@ idna==2.8
 mccabe==0.6.1
 newrelic==2.56.0.42
 pep8==1.5.7
-Pillow==3.0.0
+Pillow==8.1.1
 psycopg2==2.7.5
 pycodestyle==2.3.1
 pyflakes==1.6.0