Drop Ubuntu 20.04 support (#34557)

system/ui/SConscript

@@ -4,9 +4,6 @@ Import('env', 'arch', 'common')
 
 renv = env.Clone()
 
-UBUNTU_FOCAL = int(subprocess.check_output('[ -f /etc/os-release ] && . /etc/os-release && [ "$ID" = "ubuntu" ] && [ "$VERSION_ID" = "20.04" ] && echo 1 || echo 0', shell=True, encoding='utf-8').rstrip())
-
-if not UBUNTU_FOCAL:
 rayutil = env.Library("rayutil", ['raylib/util.cc'], LIBS='raylib')
 linked_libs = ['raylib', rayutil, common]
 renv['LIBPATH'] += [f'#third_party/raylib/{arch}/']

tools/install_ubuntu_dependencies.sh

@@ -79,16 +79,6 @@ function install_ubuntu_lts_latest_requirements() {
     python3-venv
 }
 
-# Install Ubuntu 20.04 packages
-function install_ubuntu_focal_requirements() {
-  install_ubuntu_common_requirements
-
-  $SUDO apt-get install -y --no-install-recommends \
-    libavresample-dev \
-    qt5-default \
-    python-dev
-}
-
 # Detect OS using /etc/os-release file
 if [ -f "/etc/os-release" ]; then
   source /etc/os-release
@@ -96,9 +86,6 @@ if [ -f "/etc/os-release" ]; then
     "jammy" | "kinetic" | "noble")
       install_ubuntu_lts_latest_requirements
       ;;
-    "focal")
-      install_ubuntu_focal_requirements
-      ;;
     *)
       echo "$ID $VERSION_ID is unsupported. This setup script is written for Ubuntu 24.04."
       read -p "Would you like to attempt installation anyway? " -n 1 -r
@@ -106,11 +93,7 @@ if [ -f "/etc/os-release" ]; then
       if [[ ! $REPLY =~ ^[Yy]$ ]]; then
         exit 1
       fi
-      if [ "$UBUNTU_CODENAME" = "focal" ]; then
-        install_ubuntu_focal_requirements
-      else
       install_ubuntu_lts_latest_requirements
-      fi
   esac
 
   if [[ -d "/etc/udev/rules.d/" ]]; then