fix CI file

Author: pifopi

.github/workflows/cpp-ci-serial-programs.yml

@@ -10,7 +10,6 @@ jobs:
       fail-fast: false
       matrix:
         os: [windows-2025, macos-13, ubuntu-24.04]
-        toolset: ['', '-T ClangCL']
         qt_version: ['6.9.0']
         include:
           - qt_version: '6.9.0'