update CI python version from 3.7 to 3.9

Author: jonwzheng

.github/workflows/CI.yml

@@ -64,13 +64,13 @@ jobs:
           path: RMG-database
 
       # configures the mamba environment manager and builds the environment
-      - name: Setup Miniforge Python 3.7
+      - name: Setup Miniforge Python 3.9
         uses: conda-incubator/setup-miniconda@v3
         with:
           environment-file: RMG-Py/environment.yml
           miniforge-variant: Miniforge3
           miniforge-version: latest
-          python-version: 3.7
+          python-version: 3.9
           activate-environment: rmg_env
           use-mamba: true