fix CI to force gcc 13

.github/workflows/ci.yml

@@ -1,4 +1,4 @@
-name: TerminalImageViewer CI
+name: Build and run
 
 on:
   push:
@@ -8,14 +8,20 @@ on:
 
 jobs:
   build:
-
     runs-on: ubuntu-latest
-
     steps:
     - name: Checkout
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
     - name: Install dependencies
       run: sudo apt-get install -qy imagemagick
+    - name: Validate gcc version
+      run: |
+        if [[ $(gcc --version | awk '/gcc/ && ($3+0)>13{print "gcc-13+"}') != "gcc-13+" ]]; then
+          # Script courtesy of https://stackoverflow.com/a/67791068/16134571
+          sudo apt install gcc-13 g++-13
+          sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-13 100 --slave /usr/bin/g++ g++ /usr/bin/g++-13 --slave /usr/bin/gcov gcov /usr/bin/gcov-13
+          sudo update-alternatives --set gcc /usr/bin/gcc-13
+        fi
     - name: Build
       run: make -C src
     - name: Test