[Security] Bump paramiko from 1.16.0 to 2.4.2

Bumps [paramiko](https://github.com/paramiko/paramiko) from 1.16.0 to 2.4.2. **This update includes security fixes.**
- [Release notes](https://github.com/paramiko/paramiko/releases)
- [Changelog](https://github.com/paramiko/paramiko/blob/master/NEWS)
- [Commits](paramiko/paramiko@v1.16.0...2.4.2)

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

requirements.txt

@@ -23,7 +23,7 @@ django-celery==3.2.2
 django-compressor==2.2
 jsonfield==2.0.2
 pycrypto==2.6.1
-paramiko==1.16.0
+paramiko==2.4.2
 pyasn1==0.1.9
 pycparser==2.14
 pytz==2015.7