build: add macOS support to Travis CI (#176)

Co-authored-by: Mark Lee <[email protected]>

Author: hicom150

.travis.yml

@@ -1,8 +1,12 @@
 language: node_js
+os:
+- linux
+- osx
 node_js:
-- '12'
 - '10'
+- '12'
 dist: bionic
+osx_image: xcode12
 cache:
   directories:
   - node_modules
@@ -16,6 +20,9 @@ addons:
   apt:
     packages:
     - rpm
+  homebrew:
+    packages:
+    - rpm
 deploy:
   provider: npm
   email: [email protected]