ci: build for oldest and newest python version managed by conda

Author: jorisv

.github/workflows/macos-linux-conda.yml

@@ -11,7 +11,7 @@ jobs:
       fail-fast: false
       matrix:
         os: ["ubuntu-latest", "macos-latest"]
-        python-version: ["3.10", "3.11", "3.12"]
+        python-version: ["3.8", "3.12"]
 
     steps:
     - uses: actions/checkout@v3