Bump mattnotmitt/doxygen-action from 1.9.8 to 1.12.0

Bumps [mattnotmitt/doxygen-action](https://github.com/mattnotmitt/doxygen-action) from 1.9.8 to 1.12.0.
- [Release notes](https://github.com/mattnotmitt/doxygen-action/releases)
- [Commits](mattnotmitt/doxygen-action@v1.9.8...v1.12.0)

---
updated-dependencies:
- dependency-name: mattnotmitt/doxygen-action
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

.github/workflows/flare.yml

@@ -120,7 +120,7 @@ jobs:
         rm Al* aluminum.txt aspirin.txt md17_aspirin.npz tutorial.ipynb tutorial.py
 
     - name: Run Doxygen
-      uses: mattnotmitt/doxygen-action@v1.9.8
+      uses: mattnotmitt/doxygen-action@v1.12.0
       with:
         doxyfile-path: "./Doxyfile"
         working-directory: "./docs"