switch to new drone pipeline format

.drone.yml

@@ -1,20 +1,30 @@
-pipeline:
+kind: pipeline
-  libreoffice:
+name: default
-    group: build
+
+steps:
+  - name: submodules
+    image: docker:git
+    commands:
+      - git submodule update --recursive --remote
+
+  - name: libreoffice
     image: jess/libreoffice
     commands:
       - apk add --no-cache make
       - ./compile.sh libreoffice
 
-  revealjs:
+  - name: revealjs
-    group: build
     image: python:3-alpine
     commands:
       - apk add --no-cache make
       - pip install -r requirements.txt
       - ./compile.sh revealjs
 
-  publish:
+  - name: publish
-    group: publish
     image: sbruder/drone-netlify
-    secrets: [ "netlify_key" ]
+    settings:
+      key:
+        from_secret: netlify_key
+    when:
+      branch:
+        - master