Bump pillow from 10.2.0 to 10.3.0 in /firmware/testing/python

Bumps [pillow](https://github.com/python-pillow/Pillow) from 10.2.0 to 10.3.0.
- [Release notes](https://github.com/python-pillow/Pillow/releases)
- [Changelog](https://github.com/python-pillow/Pillow/blob/main/CHANGES.rst)
- [Commits](python-pillow/Pillow@10.2.0...10.3.0)

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

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

firmware/testing/python/requirements.txt

@@ -4,7 +4,7 @@ isort==5.10.1
 lazy-object-proxy==1.7.1
 mccabe==0.6.1
 pick==1.2.0
-Pillow==10.2.0
+Pillow==10.3.0
 platformdirs==2.5.1
 pylint==2.12.2
 pyserial==3.5