Use non-interactive matplotlib for Windows CI

Author: ElliottKasoar

.github/workflows/windows.yml

@@ -11,6 +11,10 @@ jobs:
       matrix:
         python-version: ["3.10","3.11","3.12"]
 
+    # Use non-interactive backend for plotting
+    env:
+      MPLBACKEND: Agg
+
     steps:
       - uses: actions/checkout@v6