Add gh test workflow

.github/workflows/run-sml-tests.yml

@@ -0,0 +1,28 @@
+name: Run SMLUnit Unit Tests
+
+on:
+  push:
+    branches:
+      - master
+      - dev
+  pull_request:
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v3
+
+    - name: Install SML#
+      run: |
+        sudo apt-get update
+        sudo apt-get install smlnj  # Install SML/NJ
+        sudo apt-get install smlsharp  # Install SML#
+
+    - name: Run SML tests
+      run: |
+        chmod +x test
+        ./test
+