feat(ci): Cache CI results

.forgejo/workflows/eval.yaml

@@ -68,3 +68,21 @@ jobs:
         run: |
           # Enter the shell
           nix-shell --run 'colmena build --on rescue01'
+
+  push_to_cache:
+    runs-on: nix
+    needs:
+      - build_compute01
+      - build_storage01
+      - build_vault01
+      - build_web01
+      - build_web02
+      - build_rescue01
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Push to cache
+        run: nix-shell --run push-to-cache
+        env:
+          ATTIC_ENDPOINT: "https://cachix.dgnum.eu"
+          ATTIC_TOKEN: ${{ secrets.ATTIC_TOKEN }}