ci: woodpecker: use explicit 'name' key

.woodpecker/docker.yml

@@ -2,5 +2,5 @@ labels:
   type: docker
 
 pipeline:
-  test:
+- name: test
   image: hello-world

.woodpecker/exec.yml

@@ -2,12 +2,12 @@ labels:
   type: exec
 
 pipeline:
-  test:
+- name: test
   image: bash
   commands:
   - nix run 'nixpkgs#hello'
 
-  notify:
+- name: notify
   image: bash
   secrets:
   - source: matrix_homeserver