(experiment) remove extra osx from job list

.travis.yml

@@ -11,10 +11,6 @@ jobs:
       dist: trusty
     - os: osx
       osx_image: xcode12
-      env: OSX_INSTALL_DEPS=1
-    - os: osx
-      osx_image: xcode12
-      env: OSX_BUILD=1
 
 language: node_js
 node_js: "12.14.1"