Reduce minimumn requirement for jsonschema to version 3.2.0

- Currently various external dependencies caps jsonschema on the
next major release, and we jumped from requiring jsonschema 2.6.0
to 4.17.3 on jupyterlab#360 and that is causing a lot of incompatibility in
the ecosystem.

- This reduces the requirement to 3.2.0 which is also the minimun
required by jupyter-events

pyproject.toml

@@ -32,7 +32,7 @@ dependencies = [
   "importlib_metadata>=4.8.3;python_version<\"3.10\"",
   "jinja2>=3.0.3",
   "json5>=0.9.0",
-  "jsonschema>=4.17.3",
+  "jsonschema>=3.2.0",
   "jupyter_server>=1.21,<3",
   "packaging>=21.3",
   "requests>=2.28",