have CI use locked dependency versions

Author: afeld

.github/workflows/setup.yml

@@ -21,7 +21,7 @@ jobs:
         uses: mamba-org/provision-with-micromamba@main
         with:
           channel-priority: strict
-          environment-file: extras/environment.yml
+          environment-file: extras/environment.lock.yml
           cache-downloads: true
           cache-env: true
       - name: ${{ inputs.message }}