explicit rhub images for ubuntu

.github/workflows/ci.yml

@@ -19,16 +19,15 @@ jobs:
         include:
           - os: ubuntu-latest
             r-version: 'release'
+            container:
+              image: ghcr.io/r-hub/containers/ubuntu-next:latest
           - os: macos-latest
             r-version: 'release'
     steps:
       - name: checkout repository
         uses: actions/[email protected]
         with:
           fetch-depth: 1
-      - name: Install Tidy Ubuntu
-        if: matrix.os == 'ubuntu-latest'
-        run: sudo apt install -y tidy
       - name: set up R
         uses: r-lib/actions/setup-r@v2
         with:

.github/workflows/smoke-tests.yaml

@@ -13,6 +13,8 @@ jobs:
   test:
     name: smoke-tests
     runs-on: ubuntu-latest
+    container:
+      image: ghcr.io/r-hub/containers/ubuntu-next:latest
     steps:
       - name: Checkout repository
         uses: actions/[email protected]