Upgrade theme (#607)

Author: microbit-robert

.github/workflows/build.yml

@@ -37,7 +37,7 @@ jobs:
       - run: npm ci
         env:
           NODE_AUTH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-      - run: npm install --no-save @microbit-foundation/[email protected].62 @microbit-foundation/[email protected] @microbit-foundation/[email protected]
+      - run: npm install --no-save @microbit-foundation/[email protected].64 @microbit-foundation/[email protected] @microbit-foundation/[email protected]
         if: github.repository_owner == 'microbit-foundation'
         env:
           NODE_AUTH_TOKEN: ${{ secrets.GITHUB_TOKEN }}