Bump pillow from 8.2.0 to 9.0.0 in /utils/dicom_converter (#4241)

Bumps [pillow](https://github.com/python-pillow/Pillow) from 8.2.0 to 9.0.0.
- [Release notes](https://github.com/python-pillow/Pillow/releases)
- [Changelog](https://github.com/python-pillow/Pillow/blob/main/CHANGES.rst)
- [Commits](https://github.com/python-pillow/Pillow/compare/8.2.0...9.0.0)

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

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utils/dicom_converter/requirements.txt

@@ -1,4 +1,4 @@
 numpy==1.20.2
-Pillow==8.2.0
+Pillow==9.0.0
 pydicom==2.1.2
 tqdm==4.60.0