Add back whitespace workflow

.github/workflows/whitespace.yml

@@ -0,0 +1,43 @@
+name: Whitespace
+
+on:
+  pull_request:
+  push:
+    branches: ["master"]
+
+jobs:
+  whitespace:
+    runs-on: ubuntu-latest
+
+    env:
+     fix-whitespace-ver: '0.1'
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Create directory for binary
+      run: |
+        mkdir -p $HOME/.local/bin
+
+    - uses: actions/cache@v3
+      name: Cache the binary
+      id: cache
+      with:
+        path: "~/.local/bin"
+        key: fix-whitespace-${{ env.fix-whitespace-ver }}
+
+    - uses: haskell-actions/setup@v2
+      if: ${{ !steps.cache.outputs.cache-hit }}
+      with:
+        ghc-version: '9.8'
+        cabal-version: latest
+
+    - name: Install fix-whitespace
+      if: ${{ !steps.cache.outputs.cache-hit }}
+      run: |
+        cabal install --ignore-project --install-method=copy --installdir=$HOME/.local/bin fix-whitespace-${{ env.fix-whitespace-ver }}
+        strip $HOME/.local/bin/fix-whitespace
+
+    - name: Check Whitespace Conformance
+      run: |
+        $HOME/.local/bin/fix-whitespace --check