Add verify mimalloc workflow

Author: DinoV

.github/workflows/verify-mimalloc.yml

@@ -0,0 +1,38 @@
+name: Verify bundled mimalloc
+
+on:
+  workflow_dispatch:
+  push:
+    paths:
+      - 'Objects/mimalloc/**'
+      - 'Include/internal/mimalloc/**'
+      - '.github/workflows/verify-mimalloc.yml'
+  pull_request:
+    paths:
+      - 'Objects/mimalloc/**'
+      - 'Include/internal/mimalloc/**'
+      - '.github/workflows/verify-mimalloc.yml'
+
+permissions:
+  contents: read
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
+  cancel-in-progress: true
+
+jobs:
+  verify:
+    runs-on: ubuntu-slim
+    timeout-minutes: 5
+    steps:
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+        with:
+          persist-credentials: false
+      - name: Download and verify bundled mimalloc files
+        run: |
+          ./Objects/mimalloc/refresh.sh
+          # refresh.sh recreates the vendored files, so also report files
+          # that exist upstream but are not checked in.
+          git ls-files -z --others -- Objects/mimalloc/ Include/internal/mimalloc/ \
+            | xargs -0 --no-run-if-empty git add --intent-to-add --
+          git diff --exit-code Objects/mimalloc/ Include/internal/mimalloc/