updated action to preapare for spfx package

Author: nmetulev

.github/workflows/push.yml

@@ -32,3 +32,8 @@ jobs:
         if: github.repository == 'microsoftgraph/microsoft-graph-toolkit'
         env:
           NODE_AUTH_TOKEN: ${{ secrets.NPM_TOKEN }}
+      - name: Upload a Build Artifact - mgt-spfx Solution
+        uses: actions/upload-artifact@v2
+        with:
+          name: mgt-spfx solution
+          path: packages/mgt-spfx/sharepoint/*