Add an ARM flavour to CI

Author: andreasbuhr

.github/workflows/cmake.yml

@@ -105,6 +105,13 @@ jobs:
             cxx: "g++-14",
             cxxver: 20,
           }
+          - {
+            name: "Linux g++ 14 C++20 ARM",
+            os: ubuntu-24.04-arm,
+            buildtype: Release,
+            cxx: "g++-14",
+            cxxver: 20,
+          }
           - {
             name: "Linux g++ 15 (Debian) C++17",
             os: ubuntu-24.04,