.drone.yml: Build on all current Node.js LTS releases

This uses Drone.io's multi-pipeline feature.

See: https://docs.drone.io/pipeline/docker/examples/languages/node/

.drone.yml

@@ -1,3 +1,16 @@
+--
+kind: pipeline
+type: docker
+name: default
+
+steps:
+- name: build
+  image: node:10-alpine
+  commands:
+  - npm install
+  - npm run dist
+
+--
 kind: pipeline
 type: docker
 name: default
@@ -8,3 +21,15 @@ steps:
   commands:
   - npm install
   - npm run dist
+
+--
+kind: pipeline
+type: docker
+name: default
+
+steps:
+- name: build
+  image: node:14-alpine
+  commands:
+  - npm install
+  - npm run dist