ci: GitHub actions simplified

Author: henryborchers

.github/workflows/tox_matrix.yml

@@ -20,12 +20,6 @@ jobs:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
         python-version: ['3.9', '3.10', '3.11', '3.12', '3.13']
-        include:
-          - os: macos-latest
-            compiler_libcxx: libc++
-          - os: ubuntu-latest
-            compiler_libcxx: libstdc++11
-          - os: windows-latest
       fail-fast: false
     name: Python ${{ matrix.python-version }} ${{ matrix.os }} build
 
@@ -110,7 +104,6 @@ jobs:
         env:
           TOX_ENV: "${{ steps.tox-env.outputs.result }}"
           CONAN_USER_HOME: "${{steps.conan-path-script.outputs.result}}"
-          CONAN_COMPILER_LIBCXX: ${{ matrix.compiler_libcxx }}
 
         #   CIBW_SOME_OPTION: value
       - uses: actions/upload-artifact@v4