ci: use fortran-setup for GCC version testing

Author: gnikit

.github/workflows/CI.yml

@@ -20,17 +20,18 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, macos-12]
-        gcc_v: [10, 11, 12, 13] # Version of GFortran we want to use.
+        toolchain:
+          - {compiler: gcc, version: 10}
+          - {compiler: gcc, version: 11}
+          - {compiler: gcc, version: 12}
+          - {compiler: gcc, version: 13}
         build: [cmake]
         include:
           - os: ubuntu-latest
-            gcc_v: 10
             build: cmake-inline
+            toolchain:
+              - {compiler: gcc, version: 10}
     env:
-      FC: gfortran-${{ matrix.gcc_v }}
-      CC: gcc-${{ matrix.gcc_v }}
-      CXX: g++-${{ matrix.gcc_v }}
-      GCC_V: ${{ matrix.gcc_v }}
       BUILD_DIR: ${{ matrix.build == 'cmake' && 'build' || '.' }}
 
     steps:
@@ -45,22 +46,12 @@ jobs:
     - name: Install fypp
       run: pip install --upgrade fypp
 
-    - name: Install GCC compilers Linux
-      if: contains( matrix.os, 'ubuntu')
-      run: |
-        sudo add-apt-repository ppa:ubuntu-toolchain-r/test
-        sudo apt-get update
-        sudo apt-get install -y gcc-${GCC_V} g++-${GCC_V} gfortran-${GCC_V}
-        sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-${GCC_V} 100 \
-        --slave /usr/bin/gfortran gfortran /usr/bin/gfortran-${GCC_V} \
-        --slave /usr/bin/g++ g++ /usr/bin/g++-${GCC_V} \
-        --slave /usr/bin/gcov gcov /usr/bin/gcov-${GCC_V}
-
-    - name: Install GCC compilers macOS
-      if: contains( matrix.os, 'macos')
-      run: |
-          brew install gcc@${GCC_V} || brew upgrade gcc@${GCC_V} || true
-          brew link gcc@${GCC_V}
+    - name: Setup Fortran compiler
+      uses: fortran-lang/setup-fortran@v1.6.1
+      id: setup-fortran
+      with:
+        compiler: ${{ matrix.toolchain.compiler }}
+        version: ${{ matrix.toolchain.version }}
 
     - name: Configure with CMake
       if: ${{ contains(matrix.build, 'cmake') }}