ci: drop setup-node pnpm cache (fails without an Actions cache server)

Task: M0-T7

.github/workflows/ci.yml

@@ -14,7 +14,6 @@ jobs:
       - uses: actions/setup-node@v4
         with:
           node-version: 24
-          cache: pnpm
       - run: pnpm install --frozen-lockfile
       - run: pnpm lint
       - run: pnpm typecheck