Bump cryptography from 2.3.1 to 3.2

Bumps [cryptography](https://github.com/pyca/cryptography) from 2.3.1 to 3.2.
- [Release notes](https://github.com/pyca/cryptography/releases)
- [Changelog](https://github.com/pyca/cryptography/blob/master/CHANGELOG.rst)
- [Commits](pyca/cryptography@2.3.1...3.2)

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

Author: dependabot[bot]

requirements.txt

@@ -9,7 +9,7 @@ beautifulsoup4==4.6.3
 certifi==2018.8.24
 cffi==1.11.5
 chardet==3.0.4
-cryptography==2.3.1
+cryptography==3.2
 cycler==0.10.0
 h5py==2.9.0
 idna==2.7