Install tree on macOS runner

Author: mooreryan

.github/workflows/build_and_test.yml

@@ -31,6 +31,9 @@ jobs:
       - name: Checkout code
         uses: actions/checkout@v2
 
+      - run: brew install tree
+        if: matrix.os == 'macos-latest'
+
       - run: echo "LOCAL_PATH=$HOME/.local/bin" >> $GITHUB_ENV
 
       - name: Setup path