CI: speed up setup-miniconda

Author: casperdcl

.github/workflows/build.yml

@@ -41,8 +41,11 @@ jobs:
     - uses: conda-incubator/setup-miniconda@v4
       with:
         python-version: ${{ matrix.python-version }}
-        environment-file: scripts/requirements-test.yml
+        use-mamba: true
+        mamba-version: "*"
+        channels: conda-forge
         activate-environment: ${{ steps.reqs.outputs.envname }}
+        environment-file: scripts/requirements-test.yml
         run-post: false
     - id: build
       name: build
@@ -105,12 +108,15 @@ jobs:
     - uses: actions/checkout@v6
       with: {fetch-depth: 0, submodules: recursive}
     - name: set requirements
-      run: sed -ri -e '/ python /d' -e 's/(.* numpy) .*/\1=${{ matrix.numpy-version }}/' -e 's/cuda*//' -e '/tigre/d' scripts/requirements-test.yml
+      run: sed -ri -e 's/(.* python) .*/\1=${{ matrix.python-version }}/' -e 's/(.* numpy) .*/\1=${{ matrix.numpy-version }}/' -e 's/cuda*//' -e '/tigre/d' scripts/requirements-test.yml
     - uses: conda-incubator/setup-miniconda@v4
       with:
-        python-version: ${{ matrix.python-version }}
-        environment-file: scripts/requirements-test.yml
+        miniforge-version: latest
+        use-mamba: true
+        mamba-version: "*"
+        channels: conda-forge
         activate-environment: cil_dev
+        environment-file: scripts/requirements-test.yml
     - run: pip install .
     - name: test
       run: python -m unittest discover -v ./Wrappers/Python/test
@@ -169,10 +175,12 @@ jobs:
         ref: ${{ github.event.pull_request.head.sha || github.ref }} # fix SHA
     - uses: conda-incubator/setup-miniconda@v4
       with:
+        miniforge-version: latest
+        use-mamba: true
         python-version: 3.12
         mamba-version: "*"
         channels: conda-forge
-        conda-remove-defaults: "true"
+        conda-remove-defaults: true
     - uses: ruby/setup-ruby@v1
       with:
         ruby-version: '3.2'
@@ -182,7 +190,7 @@ jobs:
       run: |
         mamba install -c conda-forge -yq conda-merge
         conda-merge ../scripts/requirements-test.yml docs_environment.yml > environment.yml
-        sed -ri -e 's/cuda*//' -e '/tigre/d' environment.yml
+        sed -ri -e 's/(.* python) .*/\1=3.12/' -e 's/cuda*//' -e '/tigre/d' environment.yml
         mamba env update -n test --file environment.yml
         conda list
     - run: pip install ..