Remove ubuntu-20.04 from build targets

Author: cboulay

.github/workflows/cppcmake.yml

@@ -35,7 +35,6 @@ jobs:
       fail-fast: false
       matrix:
         config:
-        - {name: "ubuntu-20.04", os: "ubuntu-20.04",   cmake_extra: "-DLSL_BUNDLED_PUGIXML=OFF"}
         - {name: "ubuntu-22.04", os: "ubuntu-22.04",   cmake_extra: "-DLSL_BUNDLED_PUGIXML=OFF" }
         - {name: "ubuntu-24.04", os: "ubuntu-24.04",   cmake_extra: "-DLSL_BUNDLED_PUGIXML=OFF" }
         - {name: "windows-x64",  os: "windows-latest", cmake_extra: "-T v142,host=x86"}