Handle non-string values in JSON renderer (#20233)

Handle the case of async_render_with_possible_json_value's value argument
being something other than a string. This can happen, e.g., when using the
SQL sensor to extract a datetime column such as last_changed and also using
its value_template to convert that datetime to another format. This was
causing a TypeError from json.loads, but async_render_with_possible_json_value
was only catching ValueError's.