CI: cache ~/.vagrant.d/boxes

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

Author: AkihiroSuda

.github/workflows/test.yml

@@ -76,6 +76,11 @@ jobs:
       run: |
         GOOS=linux make binaries
         GOOS=linux go test -c .
+    - name: "Cache ~/.vagrant.d/boxes"
+      uses: actions/cache@v2
+      with:
+        path: ~/.vagrant.d/boxes
+        key: vagrant-${{ hashFiles('Vagrantfile*') }}
     - name: "Boot VM"
       run: |
         vagrant up