[deps] Update jsonschema requirement from ~=4.25.1 to ~=4.26.0

Updates the requirements on [jsonschema](https://github.com/python-jsonschema/jsonschema) to permit the latest version.
- [Release notes](https://github.com/python-jsonschema/jsonschema/releases)
- [Changelog](https://github.com/python-jsonschema/jsonschema/blob/main/CHANGELOG.rst)
- [Commits](python-jsonschema/jsonschema@v4.25.1...v4.26.0)

---
updated-dependencies:
- dependency-name: jsonschema
  dependency-version: 4.26.0
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Federico Capoano <f.capoano@openwisp.io>

Author: dependabot[bot]

requirements.txt

@@ -1,2 +1,2 @@
 jinja2~=3.1.6
-jsonschema~=4.25.1
+jsonschema~=4.26.0