Bump idna from 2.10 to 3.7 in /examples/sharedlinks/sharedlinks-backend

Bumps [idna](https://github.com/kjd/idna) from 2.10 to 3.7.
- [Release notes](https://github.com/kjd/idna/releases)
- [Changelog](https://github.com/kjd/idna/blob/master/HISTORY.rst)
- [Commits](kjd/idna@v2.10...v3.7)

---
updated-dependencies:
- dependency-name: idna
  dependency-type: indirect
...

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

Author: dependabot[bot]

examples/sharedlinks/sharedlinks-backend/requirements.txt

@@ -33,7 +33,7 @@ djangorestframework==3.12.2
     #   -r requirements.in
     #   django-rest-registration
     #   django-rest-swagger
-idna==2.10
+idna==3.7
     # via requests
 itypes==1.2.0
     # via coreapi