ga: only run apt-get on Linux, enable macos runner
diff --git a/.github/workflows/continuous-integration.yml b/.github/workflows/continuous-integration.yml
index 249a53f..6f6c4d3 100644
--- a/.github/workflows/continuous-integration.yml
+++ b/.github/workflows/continuous-integration.yml
@@ -4,13 +4,15 @@
 jobs:
   all:
 #    runs-on: [ ubuntu-latest, windows-latest, macos-latest ]
-    runs-on: [ ubuntu-latest ]
+    runs-on: [ ubuntu-latest, macos-latest ]
     steps:
       - name: checkout
         uses: actions/checkout@v2
       - name: install dependencies
         run: |
-          sudo apt-get install libzstd-dev
+          if [ "$RUNNER_OS" = "Linux" ]; then
+              sudo apt-get install libzstd-dev
+          fi
       - name: prepare build directory
         run: |
           cmake -E make_directory ${{runner.workspace}}/build