[deps] Update cryptography requirement from ~=43.0.0 to ~=43.0.3

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@43.0.0...43.0.3)

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

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

requirements.txt

@@ -2,5 +2,5 @@
 django>=3.2.18,!=4.0.*,<5.2
 openwisp-utils~=1.1.0
 jsonfield>=3.1.0,<4.0.0
-cryptography~=43.0.0
+cryptography~=43.0.3
 pyOpenSSL~=24.2.1