Bump autobahn from 19.5.1 to 20.12.3

Bumps [autobahn](https://github.com/crossbario/autobahn-python) from 19.5.1 to 20.12.3.
- [Release notes](https://github.com/crossbario/autobahn-python/releases)
- [Changelog](https://github.com/crossbario/autobahn-python/blob/master/docs/changelog.rst)
- [Commits](crossbario/autobahn-python@v19.5.1...v20.12.3)

---
updated-dependencies:
- dependency-name: autobahn
  dependency-type: direct:production
...

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

Author: dependabot[bot]

requirements.txt

@@ -4,7 +4,7 @@ asgiref==3.3.1
 astroid==2.4.2
 atpublic==2.3
 attrs==20.3.0
-autobahn==19.5.1
+autobahn==20.12.3
 Automat==20.2.0
 backcall==0.2.0
 bcrypt==3.2.0