Add Lean action in CI (#10)

Add Lean action in CI to make sure the package doesn't break.

By submitting this pull request, I confirm that my contribution is made
under the terms of the Apache 2.0 and MIT licenses.

Author: zhassan-aws

.github/workflows/lean_action_ci.yml

@@ -0,0 +1,14 @@
+name: Lean Action CI
+
+on:
+  push:
+  pull_request:
+  workflow_dispatch:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+      - uses: leanprover/lean-action@v1