Set python version for setup-miniconda

Author: domdfcoding

.github/workflows/conda_ci.yml

@@ -31,6 +31,7 @@ jobs:
         with:
           activate-environment: env
           conda-build-version: 3.21.0
+          python-version: "3.8"
 
       - name: Install dependencies 🔧
         run: |