Update cryptography requirement from <4,>=2.0.0 to >=2.0.0,<43

Updates the requirements on [cryptography](https://github.com/pyca/cryptography) to permit the latest version.
- [Changelog](https://github.com/pyca/cryptography/blob/main/CHANGELOG.rst)
- [Commits](pyca/cryptography@2.0...42.0.5)

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

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

requirements_optional.txt

@@ -1,2 +1,2 @@
 pillow>4.0.0
-cryptography>=2.0.0,<4
+cryptography>=2.0.0,<43