ci macos: upload dmg artifact

.github/workflows/main.yml

@@ -1,7 +1,7 @@
 name: Mac OS build
 
 on:
-  - push
+  push
 
 jobs:
   build:
@@ -42,4 +42,11 @@ jobs:
         make --jobs 8
         make install
         sudo make macosx_bundle
-
+        
+        ARTIFACT=$(ls | grep .dmg)
+        echo "Writing -${ARTIFACT} to the ARTIFACT environment variable for use in upload-artifact step"
+        echo "::set-env name=ARTIFACT::${ARTIFACT}"
+    - uses: actions/upload-artifact@v1
+      with:
+        name: ${{env.ARTIFACT}}
+        path: build/${{env.ARTIFACT}}