Bump cryptography from 2.7 to 3.2

Bumps [cryptography](https://github.com/pyca/cryptography) from 2.7 to 3.2.
- [Release notes](https://github.com/pyca/cryptography/releases)
- [Changelog](https://github.com/pyca/cryptography/blob/master/CHANGELOG.rst)
- [Commits](pyca/cryptography@2.7...3.2)

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

Author: dependabot[bot]

requirements.txt

@@ -4,7 +4,7 @@ certifi==2019.6.16
 cffi==1.12.3
 chardet==3.0.4
 crontab==0.22.6
-cryptography==2.7
+cryptography==3.2
 idna==2.8
 paramiko==2.6.0
 pkg-resources==0.0.0