Use mamba to install dependencies in ci

Author: mx-moth

.github/actions/environment/action.yaml

@@ -40,6 +40,7 @@ runs:
     - name: Install base Conda environment
       uses: conda-incubator/setup-miniconda@v2
       with:
+        mamba-version: "*"
         environment-file: continuous-integration/environment.yaml
         python-version: ${{ inputs.python-version }}
         channels: conda-forge