ci: Don't use default channel

Author: jorisv

.github/workflows/ci-ubuntu-macos.yml

@@ -28,11 +28,12 @@ jobs:
 
     - uses: conda-incubator/setup-miniconda@v3
       with:
+        miniforge-version: latest
         activate-environment: pycppad
-        auto-update-conda: true
         environment-file: .github/workflows/conda/conda-env.yml
-        python-version: 3.8
+        auto-update-conda: true
         auto-activate-base: false
+        conda-remove-defaults: true
 
     - name: Build PyCppAD
       shell: bash -el {0}

.github/workflows/ci-windows.yml

@@ -28,11 +28,12 @@ jobs:
 
     - uses: conda-incubator/setup-miniconda@v3
       with:
+        miniforge-version: latest
         activate-environment: pycppad
-        auto-update-conda: true
         environment-file: .github/workflows/conda/conda-env.yml
-        python-version: 3.8
+        auto-update-conda: true
         auto-activate-base: false
+        conda-remove-defaults: true
 
     - name: Build PyCppAD
       shell: cmd /C CALL {0}