Bump mamba-org/setup-micromamba from 2 to 3

Bumps [mamba-org/setup-micromamba](https://github.com/mamba-org/setup-micromamba) from 2 to 3.
- [Release notes](https://github.com/mamba-org/setup-micromamba/releases)
- [Commits](mamba-org/setup-micromamba@v2...v3)

---
updated-dependencies:
- dependency-name: mamba-org/setup-micromamba
  dependency-version: '3'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/conda.yml

@@ -78,7 +78,7 @@ jobs:
         - name: Checkout
           uses: actions/checkout@v6
 
-        - uses: mamba-org/setup-micromamba@v2
+        - uses: mamba-org/setup-micromamba@v3
           with:
             micromamba-version: '2.3.2-0'
             environment-file: conda/dev-environment-unix.yml
@@ -89,7 +89,7 @@ jobs:
             post-cleanup: 'all'
           if: ${{ runner.os != 'Windows' }}
 
-        - uses: mamba-org/setup-micromamba@v2
+        - uses: mamba-org/setup-micromamba@v3
           with:
             micromamba-version: '2.3.2-0'
             environment-file: conda/dev-environment-win.yml