Bump cryptography from 1.7 to 3.2

Bumps [cryptography](https://github.com/pyca/cryptography) from 1.7 to 3.2.
- [Release notes](https://github.com/pyca/cryptography/releases)
- [Changelog](https://github.com/pyca/cryptography/blob/master/CHANGELOG.rst)
- [Commits](https://github.com/pyca/cryptography/compare/1.7...3.2)
Signed-off-by: Ndependabot[bot] <support@github.com>

requirements_dev.txt

@@ -6,7 +6,7 @@ flake8
 tox==2.3.1
 coverage==4.1
 Sphinx==1.4.8
-cryptography==1.7
+cryptography==3.2
 pyyaml>=4.2b1
 face_recognition_models
 Click>=6.0