Bump pyjwt from 1.7.1 to 2.4.0 in /src/backend

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
...

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Author: dependabot[bot]

src/backend/setup.py

@@ -42,7 +42,7 @@
         "py==1.8.1",
         "pycparser==2.20",
         "pygments==2.6.1",
-        "pyjwt==1.7.1",
+        "pyjwt==2.4.0",
         "pyparsing==2.4.7",
         "pytest==5.4.2",
         "pytest-lazy-fixture==0.6.2",