Update github actions, add support for macOS (#2)

Author: mstmdev

.github/workflows/rust.yml

@@ -13,7 +13,7 @@ jobs:
   build:
     strategy:
       matrix:
-        os: [ 'ubuntu-latest', 'windows-latest' ]
+        os: [ 'ubuntu-latest', 'windows-latest', 'macos-latest' ]
 
     runs-on: ${{ matrix.os }}