chore: add a temporary workflow for testing macos gh action

.github/workflows/mactest.yml

@@ -0,0 +1,28 @@
+name: mactest
+on:
+  push:
+
+jobs:
+  e2e-macos:
+    runs-on: macos-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: upgrade bash # macos ships with a really old bash version that breaks use-nix-shell-action used below
+        run: brew install bash
+      - name: install dependencies 
+        # note: we forego default.nix and to be as close to a realistic user experience as possible
+        # all the other dependencies are already present on the runner images, so we use those
+        # and just install the missing ones via nix
+        uses: cachix/install-nix-action@v22
+        with:
+          nix_path: nixpkgs=channel:nixos-unstable
+          extra_nix_config: |
+            access-tokens = github.com=${{ secrets.GITHUB_TOKEN }}
+      - uses: rrbutani/use-nix-shell-action@v1
+        env:
+          NIXPKGS_ALLOW_UNFREE: 1 # terraform uses BSL license now, so we have to enable unfree
+        with:
+          packages: terraform,terragrunt,terraform-docs
+      - name: run test
+        run: |
+          bash --version