Bump pillow from 11.3.0 to 12.1.1 in /files

Bumps [pillow](https://github.com/python-pillow/Pillow) from 11.3.0 to 12.1.1.
- [Release notes](https://github.com/python-pillow/Pillow/releases)
- [Changelog](https://github.com/python-pillow/Pillow/blob/main/CHANGES.rst)
- [Commits](python-pillow/Pillow@11.3.0...12.1.1)

---
updated-dependencies:
- dependency-name: pillow
  dependency-version: 12.1.1
  dependency-type: direct:production
...

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

Author: dependabot[bot]

files/requirements.txt

@@ -142,7 +142,7 @@ parsley==1.3
 paste==3.10.1
 pastedeploy==3.1.0
 pebble==5.1.3
-pillow==11.3.0
+pillow==12.1.1
 prompt-toolkit==3.0.52
 propcache==0.3.2
 proto-plus==1.26.1