Bump cryptography from 2.0.3 to 3.2

Bumps [cryptography](https://github.com/pyca/cryptography) from 2.0.3 to 3.2.
- [Release notes](https://github.com/pyca/cryptography/releases)
- [Changelog](https://github.com/pyca/cryptography/blob/master/CHANGELOG.rst)
- [Commits](pyca/cryptography@2.0.3...3.2)

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

Author: dependabot[bot]

requirements.txt

@@ -9,7 +9,7 @@ celery==4.0.0
 cffi==1.7.0
 couchbase==3.0.8
 coverage==4.4.1
-cryptography==2.0.3
+cryptography==3.2
 decorator==4.1.2
 fabric3==1.14.post1
 flake8==3.5.0