chore: Use psalm-matrix workflow for good measure

Signed-off-by: Marcel Klehr <mklehr@gmx.net>

Author: marcelklehr

.github/workflows/psalm-matrix.yml

@@ -8,7 +8,13 @@
 
 name: Static analysis
 
-on: pull_request
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+      - master
+      - stable*
 
 concurrency:
   group: psalm-${{ github.head_ref || github.run_id }}