Bump cryptography from 2.5 to 3.2

Bumps [cryptography](https://github.com/pyca/cryptography) from 2.5 to 3.2.
- [Release notes](https://github.com/pyca/cryptography/releases)
- [Changelog](https://github.com/pyca/cryptography/blob/master/CHANGELOG.rst)
- [Commits](pyca/cryptography@2.5...3.2)

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

requirements.txt

@@ -7,7 +7,7 @@
 aiodns==1.1.1
 asn1crypto==0.24.0        # via cryptography
 cffi==1.11.0              # via cryptography
-cryptography==2.5       # via pyopenssl
+cryptography==3.2       # via pyopenssl
 deprecation==1.0.1        # via nicfit.py
 idna==2.6                 # via cryptography
 lxml==4.1.1