Add Ubuntu 24.04 target and eliminate Ubuntu 20.04 target.

Author: cboulay

.github/workflows/cppcmake.yml

@@ -29,10 +29,10 @@ jobs:
       fail-fast: false
       matrix:
         config:
+        - name: "ubuntu-24.04"
+          os: "ubuntu-24.04"
         - name: "ubuntu-22.04"
           os: "ubuntu-22.04"
-        - name: "ubuntu-20.04"
-          os: "ubuntu-20.04"
         - name: "windows-x64"
           os: "windows-latest"
           cmake_extra: "-T v142,host=x86"
@@ -74,10 +74,6 @@ jobs:
          version: ${{ matrix.config.qt_ver }}
          arch: ${{ matrix.config.qt_arch }}
 
-    - name: Install Qt (Ubuntu focal)
-      if: matrix.config.os == 'ubuntu-20.04'
-      run: sudo apt install qtbase5-dev
-
     - name: Install Qt (Ubuntu jammy)
       if: matrix.config.os == 'ubuntu-22.04'
       run: sudo apt install qt6-base-dev freeglut3-dev