Bump pillow from 7.1.2 to 8.1.1

Bumps [pillow](https://github.com/python-pillow/Pillow) from 7.1.2 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@7.1.2...8.1.1)

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

Author: dependabot[bot]

requirements-python37-rf31.txt

@@ -74,7 +74,7 @@ pathspec==0.8.0
 pdbpp==0.10.2
 pexpect==4.8.0
 pickleshare==0.7.5
-pillow==7.1.2
+pillow==8.1.1
 plantweb==1.2.1
 pluggy==0.13.1
 ply==3.11

requirements-python37-rf32.txt

@@ -74,7 +74,7 @@ pathspec==0.8.0
 pdbpp==0.10.2
 pexpect==4.8.0
 pickleshare==0.7.5
-pillow==7.1.2
+pillow==8.1.1
 plantweb==1.2.1
 pluggy==0.13.1
 ply==3.11