Bump mamba-org/setup-micromamba from 2.0.3 to 2.0.4 (#9)

Bumps [mamba-org/setup-micromamba](https://github.com/mamba-org/setup-micromamba) from 2.0.3 to 2.0.4.
- [Release notes](https://github.com/mamba-org/setup-micromamba/releases)
- [Commits](mamba-org/setup-micromamba@068f1ab...0dea637)

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

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

.github/workflows/sphinx-to-gh-pages.yaml

@@ -23,7 +23,7 @@ jobs:
           fetch-depth: 0
 
       - name: Set up Conda environment with Micromamba
-        uses: mamba-org/setup-micromamba@068f1ab4b37ed9b3d9f73da7db90a0cda0a48d29
+        uses: mamba-org/setup-micromamba@0dea6379afdaffa5d528b3d1dabc45da37f443fc
         with:
            environment-file: envs/environment-gh-pages.yaml
            environment-name: numeric-gh-pages