ci: cleanup, leave it to the R devs

.github/workflows/check.yml

@@ -29,16 +29,6 @@ jobs:
       uses: actions/setup-python@v4
       with:
         python-version: ${{ matrix.python-version }}
-    - name: Symlink gfortran (macOS)
-      if: runner.os == 'macOS'
-      run: |
-        # make sure gfortran is available
-        # https://github.com/actions/virtual-environments/issues/2524
-        # https://github.com/cbg-ethz/dce/blob/master/.github/workflows/pkgdown.yaml
-        sudo ln -s /usr/local/bin/gfortran-11 /usr/local/bin/gfortran
-        sudo mkdir /usr/local/gfortran
-        sudo ln -s /usr/local/Cellar/gcc@11/*/lib/gcc/11 /usr/local/gfortran/lib
-        gfortran --version
     - name: Install dependencies
       run: |
         # prerequisites
@@ -52,13 +42,14 @@ jobs:
         python -m pip install rpy2==3.5.12
     - name: install R
       if: matrix.extras == 'all'
-      uses: r-lib/actions/setup-r@v2.6.5
+      uses: r-lib/actions/setup-r@v2
       with:
         r-version: '3.6.3'
     - name: install lme4
       if: matrix.extras == 'all'
-      run: |
-         R -e "install.packages('lme4', repos='http://cran.r-project.org')"
+      uses: r-lib/actions/setup-r-dependencies@v2
+      with:
+        extra-packages: any::lme4
     - name: Install dclab with all possible dependencies
       if: matrix.extras == 'all'
       run: |