Update setup.cfg

Author: pgleeson

setup.cfg

@@ -38,7 +38,7 @@ install_requires =
    numpy
    tabulate
    attrs
-   cattrs==23.1.2  # dependency needs to be removed...
+   cattrs<23.2.1 # Issue with JSON serialisation from this version, see https://github.com/ModECI/modelspec/issues/66
    docstring-parser
    typing_extensions;python_version<'3.8'
    typing_compat;python_version<'3.8'