upgrade to setup-micromamba v2 (#4)

Author: oliver-sanders

.github/workflows/test_cylc.yml

@@ -23,7 +23,7 @@ jobs:
 
       - name: Setup Mamba
         if: ${{ matrix.micromamba_installed }} == true
-        uses: mamba-org/setup-micromamba@v1
+        uses: mamba-org/setup-micromamba@v2
 
       - name: Setup Cylc
         uses: ./

action.yml

@@ -22,7 +22,7 @@ runs:
     # install micromamba if necessary
     - name: Install Mamba
       if: steps.check_mamba.outcome == 'failure'
-      uses: mamba-org/setup-micromamba@v1
+      uses: mamba-org/setup-micromamba@v2
       with:
         init-shell: bash
         post-cleanup: 'all'