chore(deps): bump pyvista/setup-headless-display-action from 2 to 3

Bumps [pyvista/setup-headless-display-action](https://github.com/pyvista/setup-headless-display-action) from 2 to 3.
- [Release notes](https://github.com/pyvista/setup-headless-display-action/releases)
- [Commits](pyvista/setup-headless-display-action@v2...v3)

---
updated-dependencies:
- dependency-name: pyvista/setup-headless-display-action
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

.github/workflows/ex-rtd.yml

@@ -120,7 +120,7 @@ jobs:
           python-version: 3.9
 
       - name: Set up headless display
-        uses: pyvista/setup-headless-display-action@v2
+        uses: pyvista/setup-headless-display-action@v3
 
       - name: Install Python packages
         working-directory: modflow6-examples/etc

.github/workflows/ex-workflow.yml

@@ -153,7 +153,7 @@ jobs:
           python-version: ${{ matrix.python }}
 
       - name: Set up headless display
-        uses: pyvista/setup-headless-display-action@v2
+        uses: pyvista/setup-headless-display-action@v3
 
       - name: Install Python packages
         working-directory: modflow6-examples/etc