Fix micromamba CI error

.github/workflows/main.yml

@@ -34,6 +34,7 @@ jobs:
           environment-file: environment.yml
           create-args: python=${{ matrix.python-version }}
           cache-environment: true
+          micromamba-version: 1.5.6-0
       - name: Run full test suite on MacOS and Linux
         shell: bash -l {0}
         run: |