fix: updating github ci for conda build

Author: Lachlan Grose

.github/workflows/conda.yml

@@ -11,7 +11,7 @@ jobs:
       fail-fast: false
       matrix:
         os: ["ubuntu-latest",  "windows-latest","macos-latest"]
-        python-version: ["3.9"]
+        python-version: ["3.9","3.8","3.7"]
     steps:
       - uses: conda-incubator/setup-miniconda@v2
         with: