Update mopper-conda.yaml to fix python version

.github/workflows/mopper-conda.yaml

@@ -22,7 +22,7 @@ jobs:
     - name: Set up Python 3.10
       uses: actions/setup-python@v2
       with:
-        python-version: 3.10
+        python-version: '3.10'
     - name: Add conda to system path
       run: |
         # $CONDA is an environment variable pointing to the root of the miniconda directory