Bump mamba-org/setup-micromamba from 2 to 3 (#97)

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
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/gh_pages.yml

@@ -22,7 +22,7 @@ jobs:
           submodules: 'true'
 
       - name: setup micromamba
-        uses: mamba-org/setup-micromamba@v2
+        uses: mamba-org/setup-micromamba@v3
         with:
           environment-file: docs/environment.yml
           environment-name: docs