ci: Fix python matrix

Author: jorisv

.github/workflows/macos-linux-conda.yml

@@ -15,6 +15,7 @@ jobs:
         os: ["ubuntu-latest", "macos-latest"]
         cxx_options: ['', '-mavx2']
         build_type: [Release, Debug]
+        python-version: ["3.10", "3.11", "3.12"]
 
         include:
           - os: ubuntu-latest
@@ -40,7 +41,7 @@ jobs:
         activate-environment: eigenpy
         auto-update-conda: true
         environment-file: .github/workflows/conda/environment.yml
-        python-version: ['3.10', '3.11', '3.12']
+        python-version: ${{ matrix.python-version }}
 
     - uses: actions/cache@v3
       with: