feat(shell): Add an action to cache it

workflows/eval-shell.nix

@@ -0,0 +1,29 @@
+# SPDX-FileCopyrightText: 2024 Tom Hubrecht <tom.hubrecht@dgnum.eu>
+#
+# SPDX-License-Identifier: EUPL-1.2
+
+{
+  name = "Build the shell";
+  on = {
+    pull_request.branches = [ "main" ];
+    push.branches = [ "main" ];
+  };
+
+  jobs = {
+    build-shell = {
+      runs-on = "nix";
+      steps = [
+        { uses = "actions/checkout@v3"; }
+        {
+          name = "Build and cache shell";
+          run = "nix-shell -A eval-shell --run \"nix-cache -A devShell\"";
+          env = {
+            STORE_ENDPOINT = "https://tvix-store.dgnum.eu/infra-signing/";
+            STORE_USER = "admin";
+            STORE_PASSWORD = "\${{ secrets.STORE_PASSWORD }}";
+          };
+        }
+      ];
+    };
+  };
+}