cgroup2 CI: add RUNC_FLAVOR=runc

Previously we were only testing cgroup2 with crun

Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>

.github/workflows/ci.yml

@@ -434,12 +434,16 @@ jobs:
     runs-on: macos-10.15
     timeout-minutes: 40
     needs: [project, linters, protos, man]
-
+    strategy:
+      matrix:
+        runc: [runc, crun]
     steps:
       - name: Checkout containerd
         uses: actions/checkout@v2
 
       - name: Start vagrant
+        env:
+          RUNC_FLAVOR: ${{ matrix.runc }}
         run: vagrant up
 
       - name: Integration