Share Cargo cache between CI steps

.drone.yml

@@ -7,9 +7,24 @@ steps:
     image: rust:1.67
     commands:
       - cargo build
+    volumes:
+      - name: cargo-cache
+        path: /cache/cargo
+    environment:
+        CARGO_HOME: /cache/cargo
 
   - name: test
     image: rust:1.67
+    commands:
       - cargo test
+    volumes:
+      - name: cargo-cache
+        path: /cache/cargo
+    environment:
+      CARGO_HOME: /cache/cargo
     depends_on:
       - build
+
+volumes:
+  - name: cargo-cache
+    temp: {}