Bump cryptography from 3.3.2 to 42.0.2 in /requirements

Bumps [cryptography](https://github.com/pyca/cryptography) from 3.3.2 to 42.0.2.
- [Changelog](https://github.com/pyca/cryptography/blob/main/CHANGELOG.rst)
- [Commits](pyca/cryptography@3.3.2...42.0.2)

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

Signed-off-by: dependabot[bot] <[email protected]>

requirements/cext.txt

@@ -5,4 +5,4 @@
 # installed - as these dependencies are installed
 # without their dependencies.
 cffi==1.14.4
-cryptography==3.3.2
+cryptography==42.0.2