Update lighthouse action version (#790)

Author: choldgraf

.github/workflows/validate.yml

@@ -109,7 +109,7 @@ jobs:
           name: Built site ${{ github.run_number }}
           path: ./_site
       - name: Audit with Lighthouse
-        uses: treosh/lighthouse-ci-action@v10
+        uses: treosh/lighthouse-ci-action@v12
         with:
           configPath: ".github/workflows/lighthouserc.json"
           temporaryPublicStorage: true