ci: ensure tests run when highlights **.scm file changed

Author: TomJGooding

.github/workflows/pythonpackage.yml

@@ -7,6 +7,7 @@ on:
       - "**.py"
       - "**.pyi"
       - "**.css"
+      - "**.scm"
       - "**.ambr"
       - "**.lock"
       - "Makefile"