improved dronefile

.drone.yml

@@ -1,17 +1,16 @@
----
 kind: pipeline
 type: docker
 name: default
 
 steps:
   - name: format
-    image: rust:1.51
+    image: rust:1.52
     commands:
       - rustup component add rustfmt
       - cargo fmt --all -- --check
 
   - name: vendor
-    image: rust:1.51
+    image: rust:1.52
     volumes:
       - name: cache
         path: /vendor
@@ -20,7 +19,7 @@ steps:
       - cargo vendor /vendor > .cargo/config
 
   - name: test
-    image: rust:1.51
+    image: rust:1.52
     volumes:
       - name: cache
         path: /vendor
@@ -28,7 +27,7 @@ steps:
       - cargo test
 
   - name: build
-    image: rust:1.51
+    image: rust:1.52
     volumes:
       - name: cache
         path: /vendor
@@ -52,9 +51,3 @@ steps:
 volumes:
   - name: cache
     temp: {}
-
----
-kind: signature
-hmac: 4d96819ad262a0b9ba8254a3918f477a95d7930d7c893b3109da5020a9c53486
-
-...