Bump mamba-org/setup-micromamba from 1 to 2

Bumps [mamba-org/setup-micromamba](https://github.com/mamba-org/setup-micromamba) from 1 to 2.
- [Release notes](https://github.com/mamba-org/setup-micromamba/releases)
- [Commits](mamba-org/setup-micromamba@v1...v2)

---
updated-dependencies:
- dependency-name: mamba-org/setup-micromamba
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/tests.yml

@@ -56,7 +56,7 @@ jobs:
 
     - name: Setup Micromamba environment
       if: ${{ matrix.root-version }}
-      uses: mamba-org/setup-micromamba@v1
+      uses: mamba-org/setup-micromamba@v2
       with:
         environment-name: ci
         create-args: >-
@@ -71,7 +71,7 @@ jobs:
 
     - name: Setup Micromamba environment without ROOT
       if: ${{ !matrix.root-version }}
-      uses: mamba-org/setup-micromamba@v1
+      uses: mamba-org/setup-micromamba@v2
       with:
         environment-name: ci
         create-args: >-