use different python versions in mamba setup in CI

Author: morcuended

Diff for: .github/workflows/ci.yml

@@ -48,19 +48,21 @@ jobs:
       - uses: actions/checkout@v4
         with:
           fetch-depth: 0
+    
+      - name: Prepare environment file for Mamba installation
+        env:
+          PYTHON_VERSION: ${{ matrix.python-version }}
+        run: |
+          # setup correct python version
+          sed -i -e "s/- python=.*/- python=$PYTHON_VERSION/g" environment.yml
 
       - name: Setup Mamba
         uses: mamba-org/setup-micromamba@v1
         with:
-          # the create command looks like this:
-          # `micromamba create -n test-env -c conda-forge python=3.11 lstchain`
-          environment-name: test-env
-          condarc: |
-            channels:
-              - conda-forge
-          create-args: >-
-            python=${{ matrix.python-version }}
-            lstchain
+          environment-file: environment.yml
+          cache-environment: true
+          post-cleanup: 'all'
+
 
       - name: Build the package
         run: |