Test unpin cattrs

Author: pgleeson

.github/workflows/ci.yml

@@ -24,7 +24,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: [ "3.7", "3.8", "3.9", "3.10", "3.11", "3.12"]
+        python-version: [ "3.7", "3.8", "3.9", "3.10", "3.11"]
         runs-on: [ubuntu-latest, macos-latest, windows-latest]
 
     steps:

setup.cfg

@@ -39,7 +39,7 @@ install_requires =
    numpy
    tabulate
    attrs
-   cattrs<23.2.1 # Issue with JSON serialisation from this version, see https://github.com/ModECI/modelspec/issues/66
+   cattrs 
    docstring-parser
    typing_extensions;python_version<'3.8'
    typing_compat;python_version<'3.8'