add psalm workflow

Author: Sysix

.github/workflows/psalm.yml

@@ -0,0 +1,13 @@
+name: Run Psalm
+
+on: [pull_request]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+      - uses: docker://ghcr.io/psalm/psalm-github-actions
+        with:
+          composer_require_dev: true