chore: revert to mamba for GHA test env

.github/workflows/ci.yml

@@ -68,15 +68,28 @@ jobs:
       - name: Switch to Current Branch
         run: git checkout ${{ env.BRANCH }}
 
-      # Install package and deps with pip
-      - name: Install package
-        run: |
-          python -m pip install --upgrade pip
-          python -m pip install -e .[test]
+      # Install Mambaforge with conda-forge dependencies
+      - name: Setup Mambaforge
+        uses: conda-incubator/setup-miniconda@v3
+        with:
+          activate-environment: invert4geom
+          environment-file: env/testing_env.yml
+          python-version: ${{ matrix.python-version }}
+          channels: conda-forge,nodefaults
+          channel-priority: strict
+          miniforge-version: latest
+          miniforge-variant: Mambaforge
+          mamba-version: "*"
+          use-mamba: true
+          auto-activate-base: false
 
       # Show installed pkg information for postmortem diagnostic
       - name: List installed packages
-        run: pip list
+        run: mamba list
+
+      # Install the package in editable mode
+      - name: Install local package
+        run: pip install -e .
 
       - name: Run the tests
         run: >-