Update edtf requirement from <=3.0.0 to <=5.0.0

Updates the requirements on [edtf](https://github.com/ixc/python-edtf) to permit the latest version.
- [Changelog](https://github.com/ixc/python-edtf/blob/main/changelog.rst)
- [Commits](https://github.com/ixc/python-edtf/commits)

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

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

requirements.txt

@@ -95,7 +95,7 @@ pylti==0.7.0
 django-lti-provider==1.0.0
 
 pyparsing<2.3.1
-edtf<=3.0.0
+edtf<=5.0.0
 
 pbr==6.0.0 # bandit
 pyyaml==6.0.1 # bandit