bump copulas requirement

Author: rwedge

pyproject.toml

@@ -34,7 +34,7 @@ dependencies = [
     "pandas>=2.1.1;python_version>='3.12' and python_version<'3.13'",
     "pandas>=2.2.3;python_version>='3.13'",
     'tqdm>=4.29',
-    'copulas>=0.12.1',
+    'copulas>=0.13.1.dev0',
     'ctgan>=0.11.1',
     'deepecho>=0.7.0',
     'rdt>=1.18.2',