Bump pillow from 8.1.2 to 8.2.0 in /requirements (#793)

Bumps [pillow](https://github.com/python-pillow/Pillow) from 8.1.2 to 8.2.0.
- [Release notes](https://github.com/python-pillow/Pillow/releases)
- [Changelog](https://github.com/python-pillow/Pillow/blob/master/CHANGES.rst)
- [Commits](https://github.com/python-pillow/Pillow/compare/8.1.2...8.2.0)

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

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requirements/main.txt

@@ -7,6 +7,6 @@ img2pdf == 0.4.0
 pdfminer.six == 20201018
 pikepdf == 2.10.0
 pluggy == 0.13.1
-Pillow == 8.1.2
+Pillow == 8.2.0
 reportlab == 3.5.66
 tqdm == 4.59.0