Bump pyjwt from 1.7.1 to 2.4.0 in /days/051-twilio/code

Bumps [pyjwt](https://github.com/jpadilla/pyjwt) from 1.7.1 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@1.7.1...2.4.0)

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

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

Author: dependabot[bot]

days/051-twilio/code/requirements.txt

@@ -1,7 +1,7 @@
 certifi==2019.3.9
 chardet==3.0.4
 idna==2.8
-PyJWT==1.7.1
+PyJWT==2.4.0
 PySocks==1.6.8
 pytz==2019.1
 requests==2.21.0