Bump pyjwt from 1.6.4 to 2.4.0 in /release

Bumps [pyjwt](https://github.com/jpadilla/pyjwt) from 1.6.4 to 2.4.0.
- [Release notes](https://github.com/jpadilla/pyjwt/releases)
- [Changelog](https://github.com/jpadilla/pyjwt/blob/master/CHANGELOG.rst)
- [Commits](jpadilla/pyjwt@1.6.4...2.4.0)

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

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

release/requirements.txt

@@ -2,6 +2,6 @@ certifi==2018.4.16
 chardet==3.0.4
 idna==2.7
 PyGithub==1.40
-PyJWT==1.6.4
+PyJWT==2.4.0
 requests==2.19.1
 urllib3==1.23