update to mamba-org/setup-micromamba (#258)

- fix #251
- use mamba-org/setup-micromamba in CI
- note: channels are defined in the environment.yml file AND the micromamba setup because
   the channels from the yml file are only applied during use of the file but we need all channels
   during GROMACS installation (separate step)

.github/workflows/ci.yaml

@@ -52,13 +52,17 @@ jobs:
     - uses: actions/checkout@v3
 
     - name: mamba environment and package installation
-      uses: mamba-org/provision-with-micromamba@main
+      uses: mamba-org/setup-micromamba@v1
       with:
         environment-file: devtools/conda-envs/test_env.yaml
-        channel-priority: "flexible"
+        condarc: |
+           channels:
+              - conda-forge
+              - bioconda
+           channel_priority: flexible
         cache-downloads: true
-        cache-env: true
-        extra-specs: |
+        cache-environment: true
+        create-args: >-
            python=${{ matrix.python-version }}
           
     - name: Python version information
@@ -73,6 +77,7 @@ jobs:
     - name: Install pybol (fixture staging tool)
       run: |
          python -m pip install pybol
+
     - name: Install GROMACS (${{ matrix.gromacs-version }})
       # include mdanalysis here AGAIN to work around micromamba removing mdanalysis 
       # while downgrading libxml2 (see issue #252)