Bump Materials-Consortia/optimade-validator-action from 2.5.0 to 2.6.0

Bumps [Materials-Consortia/optimade-validator-action](https://github.com/Materials-Consortia/optimade-validator-action) from 2.5.0 to 2.6.0.
- [Release notes](https://github.com/Materials-Consortia/optimade-validator-action/releases)
- [Commits](Materials-Consortia/optimade-validator-action@v2.5.0...v2.6.0)

---
updated-dependencies:
- dependency-name: Materials-Consortia/optimade-validator-action
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

.github/workflows/deps_lint.yml

@@ -105,7 +105,7 @@ jobs:
         sleep 15
 
     - name: Test server, including OPTIONAL base URLs
-      uses: Materials-Consortia/optimade-validator-action@v2.5.0
+      uses: Materials-Consortia/optimade-validator-action@v2.6.0
       with:
         port: 3213
         path: /
@@ -119,7 +119,7 @@ jobs:
         sleep 15
 
     - name: Test index server, including OPTIONAL base URLs
-      uses: Materials-Consortia/optimade-validator-action@v2.5.0
+      uses: Materials-Consortia/optimade-validator-action@v2.6.0
       with:
         port: 3214
         path: /