Bump twisted from 19.2.1 to 19.7.0 (#20)

Bumps [twisted](https://github.com/twisted/twisted) from 19.2.1 to 19.7.0.
- [Release notes](https://github.com/twisted/twisted/releases)
- [Changelog](https://github.com/twisted/twisted/blob/trunk/NEWS.rst)
- [Commits](twisted/twisted@twisted-19.2.1...twisted-19.7.0)

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

requirements.txt

@@ -1,6 +1,6 @@
 inflection==0.3.1
 simplejson==3.8.2
-Twisted==19.2.1
+Twisted==19.7.0
 pytz==2016.7
 colorama==0.3.3
 pygments==2.2.0