Switch to Node 12 for CI

mramato · mramato · commit 25f380a967bd · 2020-07-27T15:39:54.000-04:00
While we updated Cesium to work on 12, we never actually made CI use it.
Traditionally we always use the active LTS for CI (which covers 12 until
October when it becomes 14).
diff --git a/.travis.yml b/.travis.yml
@@ -1,6 +1,6 @@
 language: node_js
 node_js:
-  - "10"
+  - "12"
 addons:
   chrome: stable
   firefox: latest
