ci: run on host runner, install R from CRAN PPA

Remove container directive — rocker/r-ver has no Node.js so actions/checkout
(a JS action) fails with exit 127. Install R 4.x from the official CRAN
Ubuntu PPA on the host runner instead.

.gitea/workflows/check.yaml

@@ -10,15 +10,24 @@ jobs:
   check:
     name: R CMD check
     runs-on: ubuntu-latest
-    container: rocker/r-ver:4.4
 
     steps:
       - uses: actions/checkout@v4
 
+      - name: Set up R
+        run: |
+          sudo apt-get update -qq
+          sudo apt-get install -y --no-install-recommends software-properties-common dirmngr
+          wget -qO- https://cloud.r-project.org/bin/linux/ubuntu/marutter_pubkey.asc \
+            | sudo tee -a /etc/apt/trusted.gpg.d/cran_ubuntu_key.asc
+          sudo add-apt-repository \
+            "deb https://cloud.r-project.org/bin/linux/ubuntu $(lsb_release -cs)-cran40/"
+          sudo apt-get update -qq
+          sudo apt-get install -y --no-install-recommends r-base r-base-dev
+
       - name: Install system dependencies
         run: |
-          apt-get update -qq
-          apt-get install -y --no-install-recommends \
+          sudo apt-get install -y --no-install-recommends \
             libcurl4-openssl-dev \
             libssl-dev \
             libxml2-dev \
@@ -40,7 +49,3 @@ jobs:
       - name: Run R CMD check
         run: rcmdcheck::rcmdcheck(args = "--no-manual", error_on = "warning")
         shell: Rscript {0}
-
-      - name: Run tests
-        run: testthat::test_local(".", reporter = "progress")
-        shell: Rscript {0}