Bump pillow from 7.0.0 to 8.1.1 in /v2functions

Bumps [pillow](https://github.com/python-pillow/Pillow) from 7.0.0 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@7.0.0...8.1.1)

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

Author: dependabot[bot]

v2functions/requirements.txt

@@ -8,6 +8,6 @@ six==1.11.0
 # Additional packages
 requests==2.20.1
 feedparser==5.2.1
-Pillow==7.0.0
+Pillow==8.1.1
 numpy==1.18.1
 onnxruntime==1.4.0