Bump jsonschema from 3.2.0 to 4.21.0

Bumps [jsonschema](https://github.com/python-jsonschema/jsonschema) from 3.2.0 to 4.21.0.
- [Release notes](https://github.com/python-jsonschema/jsonschema/releases)
- [Changelog](https://github.com/python-jsonschema/jsonschema/blob/main/CHANGELOG.rst)
- [Commits](python-jsonschema/jsonschema@v3.2.0...v4.21.0)

---
updated-dependencies:
- dependency-name: jsonschema
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

requirements.txt

@@ -22,7 +22,7 @@ incremental==16.10.1
 Jinja2==2.10.1
 jsonpatch==1.22
 jsonpointer==2.0
-jsonschema==3.2.0
+jsonschema==4.21.0
 keyring==18.0.1
 language-selector==0.1
 launchpadlib==1.10.13