Revert "Bump actions/cache from 5 to 6 (#751)" (#752)

This reverts commit 31efe13.

Author: ross0x01

.github/workflows/desktop-build.yml

@@ -98,7 +98,7 @@ jobs:
         id: pnpm-cache
 
       - name: Setup pnpm cache
-        uses: actions/cache@v6
+        uses: actions/cache@v5
         with:
           path: ${{ steps.pnpm-cache.outputs.STORE_PATH }}
           key: ${{ runner.os }}-pnpm-store-${{ hashFiles('packages/desktop/pnpm-lock.yaml') }}