fetch the gh-pages branch from the remote, merge any changes if it ex…

…ists, or create it if it doesn't exist

.github/workflows/pr_ci_playwright_e2e.yaml

@@ -47,16 +47,29 @@ jobs:
         run: |
           sudo yarn install
 
+      - name: Cache Playwright browsers
+        uses: actions/cache@v3
+        id: playwright-cache
+        with:
+          path: ~/.cache/ms-playwright
+          key: playwright-browsers-${{ runner.os }}-${{ hashFiles('**/package-lock.json', '**/yarn.lock') }}
+          restore-keys: |
+            playwright-browsers-${{ runner.os }}-
+
       - name: Install Playwright Browsers
+        if: steps.playwright-cache.outputs.cache-hit != 'true'
         working-directory: ./frontend
-        run: |
-          sudo yarn playwright install --with-deps
+        run: sudo yarn playwright install --with-deps
+
 
       - name: Ensure gh-pages branch exists
+        if: always()
         run: |
-          git fetch
-          if ! git show-ref --verify --quiet refs/heads/gh-pages; then
-            echo "gh-pages branch does not exist. Creating..."
+          git fetch origin gh-pages
+          if git rev-parse --verify origin/gh-pages; then
+            git checkout gh-pages
+            git reset --hard origin/gh-pages
+          else
             git checkout --orphan gh-pages
             git rm -rf .
             echo "# GitHub Pages" > index.html