CI: also use CLDR cache in build step

Author: akx

.github/workflows/ci.yml

@@ -106,6 +106,10 @@ jobs:
       - uses: actions/checkout@v6
         with:
           persist-credentials: false
+      - uses: actions/cache@v5
+        with:
+          path: cldr
+          key: cldr-${{ hashFiles('scripts/*cldr*') }}
       - uses: actions/setup-python@v6
         with:
           python-version: "3.14"