Fix URL definition to adapt to new version of pydantic

[chaen]

From pydantic 2.10, URL should be defined a bit differently

https://pydantic.dev/articles/pydantic-v2-10-release#migrate-to-subclassing-instead-of-annotated-approach-for-pydantic-url-types

while doing the change, they broke the existing (but are already fixing it): pydantic/pydantic#10914

For us, this translate into the tests failing with stacktrace looking like

                    forbid_inf_nan_check,
                    schema,
                )
            else:
                # It's rare that we'd get here, but it's possible if we add a new constraint and forget to handle it
                # Most constraint errors are caught at runtime during attempted application
>               raise RuntimeError(f"Unable to apply constraint '{constraint}' to schema of type '{schema_type}'")
E               RuntimeError: Unable to apply constraint 'host_required' to schema of type 'function-wrap'

../../../miniforge3/envs/diracx-dev/lib/python3.11/site-packages/pydantic/_internal/_known_annotated_metadata.py:285: RuntimeError

[martynia]

OK, so I was not the only one affected. (#269)