add catalog.yml to package data

Author: edwardchalstrey1

pyproject.toml

@@ -85,5 +85,11 @@ markers = [
     "slow: all time-consuming tests",
 ]
 
+[tool.setuptools]
+include-package-data = true
+
+[tool.setuptools.package-data]
+pygambit = ["catalog.yml"]
+
 [tool.setuptools.dynamic]
 version = {file = "build_support/GAMBIT_VERSION"}